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1

Detection of radiation effects using recombinant bioluminescent Escherichia coli strains  

Microsoft Academic Search

Effects of ionizing radiation (0.1–500 Gy) on recombinant Escherichia coli cells containing the stress promoters recA, grpE, or katG, fused to luxCDABE, were characterized by monitoring transcriptional responses reflected by the bioluminescent output. The minimum dose of gamma-irradiation\\u000a detected by E. coli DPD2794 (recA::luxCDABE) was about 1.5 Gy, while the maximum response was obtained at 200 Gy. The amount of

Jiho Min; Chang Woo Lee; Seung-Hyeun Moon; Robert A. LaRossa; Man Bock Gu

2000-01-01

2

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

3

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

4

Development of a biosensor for on-line detection of tributyltin with a recombinant bioluminescent Escherichia coli strain  

Microsoft Academic Search

A biosensor was developed for the detection of tributyltin (TBT), using a bioluminescent recombinant Escherichia coli:: luxAB strain. Dedicated devices allowed the on-line measurement of bioluminescence, pH and dissolved oxygen values and the feed-back regulation of temperature. Bacterial physiology was monitored by the measurement of the cellular density, respiratory activity and the intracellular level of ATP, glucose and acetate levels.

G. Thouand; H. Horry; M. J. Durand; P. Picart; L. Bendriaa; P. Daniel; M. S. DuBow

2003-01-01

5

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

6

A real-time monitoring and detection instrument for analysis of the effects of O 3 on bioluminescent Escherichia coli on agar surfaces—potential applications to the food industry  

Microsoft Academic Search

An instrument was fabricated to measure the real-time response of a bioluminescent construct of Escherichia coli to ozone treatment. The bioluminescent output from E. coli inoculated on nutrient agar plates was measured with a photomultiplier tube coupled to a lock-in amplifier and the ozone concentration was calculated from absorption measurements from a 254 nm source. Data from the two measurement

Boon Kiat Tan; Ian A. Watson; Roger Parton; Ian Peden

2005-01-01

7

Immobilization of bioluminescent Escherichia coli cells using natural and artificial fibers treated with polyethyleneimine  

Microsoft Academic Search

Biosensors based on whole-cell bioluminescence have the potential to become a cost-effective alternative to conventional detection methods upon validation of target selectivity and sensitivity. However, quantitative analysis of bioluminescence is greatly hindered due to lack of control over the total number of cells in a suspending culture. In this study, the effect of surface properties of genetically engineered luminous E.

Yi-Fang Chu; Chia-Hua Hsu; Pavan K. Soma; Y. Martin Lo

2009-01-01

8

Bacteriophage-based biosorbents coupled with bioluminescent ATP assay for rapid concentration and detection of Escherichia coli  

Microsoft Academic Search

Wild type T4 bacteriophage and recombinant T4 bacteriophages displaying biotin binding peptide (BCCP) and cellulose binding module (CBM) on their heads were immobilized on nano-aluminum fiber-based filter (Disruptor™), streptavidin magnetic beads and microcrystalline cellulose, respectively. Infectivity of the immobilized phages was investigated by monitoring the phage-mediated growth inhibition of bioluminescent E. coli B and cell lysis using bioluminescent ATP assay.

O. Minikh; M. Tolba; L. Y. Brovko; M. W. Griffiths

2010-01-01

9

Real-Time Monitoring of Escherichia coli O157:H7 Adherence to Beef Carcass Surface Tissues with a Bioluminescent Reporter  

Microsoft Academic Search

A method for studying bacteria that are attached to carcass surfaces would eliminate the need for exogenous sampling and would facilitate understanding the interaction of potential human food-borne pathogens with food animal tissue surfaces. We describe such a method in which we used a bioluminescent reporter strain of Escherichia coli O157:H7 that was constructed by transformation with plasmid pCGLS1, an

GREGORY R. SIRAGUSA; KEVIN NAWOTKA; STANLEY D. SPILMAN; PAMELA R. CONTAG; CHRISTOPHER H. CONTAG

1999-01-01

10

Bacterial bioluminescent emission from recombinant Escherichia coli harboring a recA::luxCDABE fusion  

Microsoft Academic Search

This paper describes the quantitative evaluation of a bioluminescence assay for DNA damaging agents with respect to the linearity, sensitivity, specificity and dependence on the cell culture status. A recombinant bacterium, DPD2794, harboring a plasmid with a recA promoter fused to the luxCDABE operon, showed a very sensitive response to DNA-damaging stress. DPD2794 was found to show no noticeable response

Man Bock Gu; Jiho Min; Robert A LaRossa

2000-01-01

11

Bacteriophage-based biosorbents coupled with bioluminescent ATP assay for rapid concentration and detection of Escherichia coli.  

PubMed

Wild type T4 bacteriophage and recombinant T4 bacteriophages displaying biotin binding peptide (BCCP) and cellulose binding module (CBM) on their heads were immobilized on nano-aluminum fiber-based filter (Disruptor), streptavidin magnetic beads and microcrystalline cellulose, respectively. Infectivity of the immobilized phages was investigated by monitoring the phage-mediated growth inhibition of bioluminescent E. coli B and cell lysis using bioluminescent ATP assay. The results showed that phage immobilization resulted in a partial loss of infectivity as compared with the free phage. Nevertheless, the use of a biosorbent based on T4 bacteriophage immobilized on Disruptor filter coupled with a bioluminescent ATP assay allowed simultaneous concentration and detection of as low as 6 x 10(3)cfu/mL of E. coli in the sample within 2h with high accuracy (CV=1-5% in log scale). Excess of interfering microflora at levels 60-fold greater than the target organism did not affect the results when bacteriophage was immobilized on the filter prior to concentration of bacterial cells. PMID:20561957

Minikh, O; Tolba, M; Brovko, L Y; Griffiths, M W

2010-06-01

12

In vivo bioluminescence imaging of Escherichia coli O104:H4 and role of aerobactin during colonization of a mouse model of infection  

PubMed Central

Background A major outbreak of bloody diarrhea associated with Shiga toxin-producing Escherichia coli O104:H4 occurred early in 2011, to which an unusual number of hemolytic uremic syndrome cases were linked. Due to limited information regarding pathogenesis and/or virulence properties of this particular serotype, we investigated the contribution of the aerobactin iron transport system during in vitro and in vivo conditions. Results A bioluminescent reporter construct was used to perform real-time monitoring of E. coli O104:H4 in a mouse model of infection. We verified that our reporter strain maintained characteristics and growth kinetics that were similar to those of the wild-type E. coli strain. We found that the intestinal cecum of ICR (CD-1) mice was colonized by O104:H4, with bacteria persisting for up to 7?days after intragastric inoculation. MALDI-TOF analysis of heat-extracted proteins was performed to identify putative surface-exposed virulence determinants. A protein with a high similarity to the aerobactin iron receptor was identified and further demonstrated to be up-regulated in E. coli O104:H4 when grown on MacConkey agar or during iron-depleted conditions. Because the aerobactin iron acquisition system is a key virulence factor in Enterobacteriaceae, an isogenic aerobactin receptor (iutA) mutant was created and its intestinal fitness assessed in the murine model. We demonstrated that the aerobactin mutant was out-competed by the wild-type E. coli O104:H4 during in vivo competition experiments, and the mutant was unable to persist in the cecum. Conclusion Our findings demonstrate that bioluminescent imaging is a useful tool to monitor E. coli O104:H4 colonization properties, and the murine model can become a rapid way to evaluate bacterial factors associated with fitness and/or colonization during E. coli O104:H4 infections.

2012-01-01

13

Ex vivo bioluminescence imaging of late gestation ewes following intrauterine inoculation with lux-modified Escherichia coli  

Microsoft Academic Search

Our objectives were to develop an ovine model for Escherichia coli-induced preterm delivery, and monitor E. coli (lux modified for photonic detection) invasion of the fetal environment—ewes (124±18d of gestation) received intrauterine inoculations using E. coli-lux as follows: control (n=5), 1.2×106CFU\\/ml (n=5), 5.6×106CFU\\/ml (n=5) E. coli-lux. Preterm delivery occurred between 48 and 120h post-inoculation in 60%, 60% of ewes infected

K. Moulton; P. Ryan; D. Christiansen; R. Hopper; C. Klauser; W. Bennett; S. Rodts-Palenik; S. Willard

2009-01-01

14

ESCHERICHIA COLI  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli is a major commensal of the human intestine, and for years, the organism was regarded as having low virulence. In the 1920's, E. coli was recognized as a cause of urinary tract infections and in the 1940's as a cause of gastroenteritis in infants. The identification of a wide rang...

15

A Stable Bioluminescent Construct of Escherichia coli O157:H7 for Hazard Assessments of Long-Term Survival in the Environment  

PubMed Central

A chromosomally lux-marked (Tn5 luxCDABE) strain of nontoxigenic Escherichia coli O157:H7 was constructed by transposon mutagenesis and shown to have retained the O157, H7, and intimin phenotypes. The survival characteristics of this strain in the experiments performed (soil at ?5, ?100, and ?1,500 kPa matric potential and artificial groundwater) were indistinguishable from the wild-type strain. Evaluation of potential luminescence was found to be a rapid, cheap, and quantitative measure of viable E. coli O157:H7 Tn5 luxCDABE populations in environmental samples. In the survival studies, bioluminescence of the starved populations of E. coli O157:H7 Tn5 luxCDABE could be reactivated to the original levels of light emission, suggesting that these populations remain viable and potentially infective to humans. The attributes of the construct offer a cheap and low-risk substitute to the use of verocytotoxin-producing E. coli O157:H7 in long-term survival studies.

Ritchie, Jennifer M.; Campbell, Graeme R.; Shepherd, Jill; Beaton, Yvonne; Jones, Davey; Killham, Ken; Artz, Rebekka R. E.

2003-01-01

16

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

17

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

18

Diarrheagenic Escherichia coli  

PubMed Central

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

Nataro, James P.; Kaper, James B.

1998-01-01

19

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...

20

Escherichia coli Diarrhea  

Microsoft Academic Search

\\u000a During the 1940s and 1950s, a series of outbreaks of diarrhea in hospital newborn nurseries were reported in which the etiologic\\u000a agent appeared to be Escherichia coli identified by serotype. These strains became known as enteropathogenic E. coli (EPEC). Since the Second International Symposium on EPEC in 1995, EPEC strains have been renamed typical EPEC (tEPEC) to\\u000a distinguish them from

Herbert L. DuPont; M. Teresa Estrada-Garcia; Zhi-Dong Jiang

21

Genetic recombination. [Escherichia coli  

SciTech Connect

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

Stahl, F.W.

1987-02-01

22

Torus generated by Escherichia coli  

NASA Astrophysics Data System (ADS)

The bioluminescence images of unstirred cultures show that lux reporter E. coli (0.10 mg biomass per ml of the broth medium) in 6.4-10 mm diameter circular containers induce center-fluid-rising toroidal convection of ?1 mm/min. The bioconvective torus is stable in a Teflon vessel and is deformed by 3.2-4.4 mm wavelength azimuthal waves in polystyrene or glass vessels.

Šimkus, R.; Kirejev, V.; Meškien?, R.; Meškys, R.

2009-02-01

23

Detection of E. coli in beach water within 1 hour using immunomagnetic separation and ATP bioluminescence.  

PubMed

The contamination of beach waters occurs from the discharge of storm water and sanitary sewer overflows containing faecal material. Additional faecal material derives from discharge of animals and waterfowl. In order to protect public from exposure to faecal-contaminated water, it is required to test enteric indicators in beach water. The problem is that the traditional culture-based methods cannot meet this goal because it takes too long (>24 h), so the results are not available until a day later. A rapid method for testing beach water for Escherichia coli within 1 h has been developed. Immunomagnetic separation (IMS) and ATP bioluminescence were used for selective capture and quantification, respectively. This rapid method was compared to the current method (m-TEC) using beach water samples. The beach samples were prefiltered with a 20 microm pore size filter in order to remove algae, plant debris and large particles. The results showed that the prefiltration step did not trap the bacteria which were present in the original water samples. The prefiltered water was then passed through a 0.45 microm pore size filter for concentration. The deposited bacteria were resuspended and then mixed with superparamagnetic polystyrene beads (diameter of 0.6 microm) that were coated with E. coli antibodies. After IMS, the quantification of the E. coli was done by ATP bioluminescence. The results obtained with IMS-ATP bioluminescence correlated well with the plate count method (Rsq = 0.93). The detection limit of the assay was about 20 CFU/100 mL, which is well below the US EPA limits for recreational water. The entire procedure can be completed in less than 1 hour. The necessary equipment is portable and was tested on-site. PMID:14981644

Lee, JiYoung; Deininger, Rolf A

24

EXTRAINTESTINAL PATHOGENIC ESCHERICHIA COLI (EXPEC)  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

25

21 CFR 866.3255 - Escherichia coli serological reagents.  

Code of Federal Regulations, 2010 CFR

...reagents consist of Escherichia coli antisera conjugated with a...used to identify Escherichia coli directly from clinical...microorganism. Although Escherichia coli constitutes the greater...notification procedures in subpart E of part 807 of this chapter...

2009-04-01

26

21 CFR 866.3255 - Escherichia coli serological reagents.  

Code of Federal Regulations, 2010 CFR

...reagents consist of Escherichia coli antisera conjugated with a...used to identify Escherichia coli directly from clinical...microorganism. Although Escherichia coli constitutes the greater...notification procedures in subpart E of part 807 of this chapter...

2010-04-01

27

21 CFR 866.3255 - Escherichia coli serological reagents.  

Code of Federal Regulations, 2013 CFR

...reagents consist of Escherichia coli antisera conjugated with a...used to identify Escherichia coli directly from clinical...microorganism. Although Escherichia coli constitutes the greater...notification procedures in subpart E of part 807 of this chapter...

2013-04-01

28

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

EPA Science Inventory

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

29

In vivo bioluminescence for studying the adhesion of bacteria  

Microsoft Academic Search

A bioluminescent phenotype of Escherichia coli was employed to follow bacterial uptake onto model polystyrene surfaces. Attachment from suspension was rapid and the isotherm exhibited Langmuirian characteristics. The uptake pattern was reflected in both real?time bioluminescence measurement of attached bacteria in a luminometer and in conventional viable count determination. Treatment of attached bacteria with 3 biocidal agents produced a rank

S. P. Denyer; S. A. A. Jassim; G. S. A. B. Stewart

1991-01-01

30

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

31

Robust growth of Escherichia coli  

PubMed Central

Summary The quantitative study of the cell growth [1-5] has led to many fundamental insights in our understanding of a wide range of subjects from cell cycle [6-9] to senescence [10]. Of particular importance is the growth rate, whose constancy represents a physiological steady state of an organism. Recent studies, however, suggest that the rate of elongation during exponential growth of bacterial cells decreases cumulatively with replicative age for both asymmetrically [11] and symmetrically [12,13] dividing organisms, implying that a “steady-state” population consists of individual cells that are never in a steady state of growth. To resolve this seeming paradoxical observation, we studied the long-term growth and division patterns of Escherichia coli cells by employing a microfluidic device designed to follow steady state growth and division of a large number of cells at a defined reproductive age. Our analysis of ~105 individual cells reveals a remarkable stability of growth of the mother cell inheriting the same pole for hundreds of generations. We further show that death of E. coli is not purely stochastic but is the result of accumulating damages. We conclude that E. coli, unlike all other aging model systems studied to date, has a robust mechanism of growth that is decoupled from cell death.

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

2010-01-01

32

DETECTION AND CHARACTERIZATION OF PATHOGENIC ESCHERICHIA COLI  

Technology Transfer Automated Retrieval System (TEKTRAN)

A comparison was made of the relative efficiencies of three enrichment media, Rapid-Chek E. coli O157:H7 Enrichment Broth (REB), BCM Escherichia coli O157:H7 Enrichment Broth (BCM), and modified E. coli broth containing novobiocin (mEC+n), and four selective plating media for detection/isolation of...

33

Nonchemotactic Mutants of Escherichia coli  

PubMed Central

We have isolated 40 mutants of Escherichia coli which are nonchemotactic as judged by their failure to swarm on semisolid tryptone plates or to make bands in capillary tubes containing tryptone broth. All the mutants have normal flagella, a fact shown by their shape and reaction with antiflagella serum. All are fully motile under the microscope and all are sensitive to the phage chi. Unlike its parent, one of the mutants, studied in greater detail, failed to show chemotaxis toward oxygen, glucose, serine, threonine, or aspartic acid. The failure to exhibit chemotaxis does not result from a failure to use the chemicals. The swimming of this mutant was shown to be random. The growth rate was normal under several conditions, and the growth requirements were unchanged. Images

Armstrong, John B.; Adler, Julius; Dahl, Margaret M.

1967-01-01

34

Negative Chemotaxis in Escherichia coli  

PubMed Central

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

Tso, Wung-Wai; Adler, Julius

1974-01-01

35

Peptidoglycan Hydrolases of Escherichia coli  

PubMed Central

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

van Heijenoort, Jean

2011-01-01

36

Strategies for Protein Overproduction in Escherichia coli.  

ERIC Educational Resources Information Center

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

Mott, John E.

1984-01-01

37

MANURE DECREASES ESCHERICHIA COLI ATTACHMENT TO SOIL  

Technology Transfer Automated Retrieval System (TEKTRAN)

Attachment of bacteria to soil is an important component of bacterial fate and transport. Escherichia. coli are commonly used as indicators of fecal contamination in the environment. Despite the fact that E. coli are derived exclusively from feces/manure, relatively little is known about the effect...

38

Microcins and urovirulence in Escherichia coli  

Microsoft Academic Search

Urinary tract infections are among the most common infectious diseases encountered in humans and Escherichia coli is their leading etiologic agent. Uropathogenic E. coli encompasses a group of bacteria possessing a variable virulence gene assortment. It is generally agreed that many urovirulence factors remain to be discovered and that this information is required to gain knowledge on the pathogenic processes

María F. Azpiroz; María Eloisa Poey; Magela Laviña

2009-01-01

39

Clinical Characteristics of Adult Escherichia coli Meningitis  

Microsoft Academic Search

SUMMARY: The clinical characteristics and therapeutic outcomes of adult meningitis due to Escherichia coli alone have not been examined adequately. In this study, we analyzed the clinical and laboratory data of 15 adult patients with monomicrobial E. coli meningitis. The 15 patients, collected over a period of 18 years (January 1986 - December 2003), included 7 men and 8 women,

Tzu-Ming Yang; Cheng-Hsien Lu; Chi-Ren Huang; Hui-Hong Tsai; Nai-Wen Tsai; Ping-Yu Lee; Chun-Chih Chien; Wen-Neng Chang

40

Natural plasmid transformation in Escherichia coli  

Microsoft Academic Search

AlthoughEscherichia coli does not have a natural transformation process, strains ofE. coli can incorporate extracellular plasmids into cytoplasm ‘naturally’ at low frequencies. A standard method was developed in which stationary phase cells were concentrated, mixed with plasmids, and then plated on agar plates with nutrients which allowed cells to grow. Transformed cells could then be selected by harvesting cells and

Suh-Der Tsen; Suh-Sen Fang; Mei-Jye Chen; Jun-Yi Chien; Chih-Chun Lee; Darwin Han-Lin Tsen

2002-01-01

41

Natural Plasmid Transformation in Escherichia coli  

Microsoft Academic Search

Although Escherichia coli does not have a natural transformation process, strains of E. coli can incorporate extracellular plasmids into cytoplasm ‘naturally’ at low frequencies. A standard method was developed in which stationary phase cells were concentrated, mixed with plasmids, and then plated on agar plates with nutrients which allowed cells to grow. Transformed cells could then be selected by harvesting

Suh-Der Tsen; Suh-Sen Fang; Mei-Jye Chen; Jun-Yi Chien; Chih-Chun Lee; Darwin Han-Lin Tsen

2002-01-01

42

Phenotypic Dissociation in an Escherichia coli Population  

Microsoft Academic Search

It was shown in the preceding work [1] that Escherichia coli colonies have an elaborate spatial structure. This structure is arbitrarily divided into four zones. Two cell forms of E. coli (coccobacteria and long rodshaped bacteria) are observed in growing colonies. Formation of long rods (filaments) can be induced by mutations and chemical agents [2]. The goal of this work

V. V. Kravchenko; A. B. Medvinskii; G. R. Ivanitskii

2000-01-01

43

Transcriptional proofreading in Escherichia coli.  

PubMed Central

A novel transcriptional proofreading mechanism associated with the beta-subunit of wild-type RNA polymerase from Escherichia coli is suggested from the following data. The purified holoenzyme contains an NTPase activity which specifically converts noncognate NTPs to their corresponding NDP in a template-dependent manner during in vitro transcription of synthetic single- and double-stranded templates. In contrast, purified enzyme from an rpoB mutant which shows increased transcriptional error lacked template-dependent NTP hydrolytic activity. The NTP hydrolytic activity of wild-type enzyme was critically dependent on the integrity of the initiation complex, and required continued transcriptional elongation. Transcription and translation of the lacZ gene proceeded 17% faster in the mutant than in its wild-type parent. These results are discussed in terms of a proofreading model in which the rate of transcription is limited by proofreading events that involve recognition and hydrolysis of noncognate NTPs before they can be misincorporated into RNA. Images

Libby, R T; Nelson, J L; Calvo, J M; Gallant, J A

1989-01-01

44

Succinate production in Escherichia coli.  

PubMed

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 the production of four-carbon dicarboxylic acid. Important features of a succinate production system are to achieve an optimal balance of reducing equivalents generated by consumption of the feedstock, while maximizing the amount of carbon channeled into the product. Aerobic and anaerobic production strains have been developed and applied to production from glucose and 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, the requirement for efficient recovery of succinate, and the reliability of the performance under scaleup are important in the overall process. The costs of the overall biorefinery-compatible process will determine the economic commercialization of succinate and its impact in larger chemical markets. PMID:21932253

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

2011-09-20

45

Growth rate of Escherichia coli.  

PubMed Central

It should be possible to predict the rate of growth of Escherichia coli of a given genotype in a specified environment. The idea that the rate of synthesis of ATP determines the rate of growth and that the yield of ATP determines the yield of growth is entrenched in bacterial physiology, yet this idea is inconsistent with experimental results. In minimal media the growth rate and yield vary with the carbon source in a manner independent of the rate of formation and yield of ATP. With acetate as the carbon source, anapleurotic reactions, not ATP synthesis, limit the growth rate. For acetate and other gluconeogenic substrates the limiting step appears to be the formation of triose phosphate. I conclude that the rate of growth is controlled by the rate of formation of a precursor metabolite and, thus, of monomers such as amino acids derived from it. The protein-synthesizing system is regulated according to demand for protein synthesis. I examine the conjecture that the signal for this regulation is the ratio of uncharged tRNA to aminoacyl-tRNA, that this signal controls the concentration of guanosine tetraphosphate, and that the concentration of guanosine tetraphosphate controls transcription of rrn genes. Differential equations describing this system were solved numerically for steady states of growth; the computed values of ribosomes and guanosine tetraphosphate and the maximal growth rate agree with experimental values obtained from the literature of the past 35 years. These equations were also solved for dynamical states corresponding to nutritional shifts up and down.

Marr, A G

1991-01-01

46

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

47

BAM: Diarrheagenic Escherichia coli  

Center for Food Safety and Applied Nutrition (CFSAN)

... a small loopful of growth from TSAYE ... Coliforms, fecal coliforms, Escherichia coli and enteropathogenic E ... Escherichia coli and the Coliform Bacteria. ... More results from www.fda.gov/food/foodscienceresearch/laboratorymethods

48

Escherichia coli growth under modeled reduced gravity  

Microsoft Academic Search

Bacteria exhibit varying responses to modeled reduced gravity that can be simulated by clino-rotation. WhenEscherichia coli was subjected to different rotation speeds during clino-rotation, significant differences between modeled reduced gravity\\u000a and normal gravity controls were observed only at higher speeds (30–50 rpm). There was no apparent affect of removing samples\\u000a on the results obtained. WhenE. coli was grown in minimal

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

2004-01-01

49

Native valve Escherichia coli endocarditis following urosepsis  

PubMed Central

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

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

2013-01-01

50

Expanding the Genetic Code of Escherichia coli  

Microsoft Academic Search

A unique transfer RNA (tRNA)\\/aminoacyl-tRNA synthetase pair has been generated that expands the number of genetically encoded amino acids in Escherichia coli. When introduced into E. coli, this pair leads to the in vivo incorporation of the synthetic amino acid O-methyl-L-tyrosine into protein in response to an amber nonsense codon. The fidelity of translation is greater than 99%, as determined

Lei Wang; Ansgar Brock; Brad Herberich; Peter G. Schultz

2001-01-01

51

Inactivation of Escherichia coli by photocatalytic oxidation  

Microsoft Academic Search

The inactivation of Escherichia coli (Ecoli) was studied in presterilized surface water sample using titanium dioxide as the photocatalyst under irradiation of BLF Fluorescent lamps. Inactivation of E. coli ( 103 CFU\\/mL) was achieved in 60 min in the presence of 1.0 mg Ti02 \\/ mL. Photocatalytic inactivation data was evaluated in terms of first order rate equation N\\/N0 =

Miray Bekbölet; Claudia V. Araz

1996-01-01

52

Monitoring and classification of PAH toxicity using an immobilized bioluminescent bacteria  

Microsoft Academic Search

An immobilized recombinant bioluminescent Escherichia coli strain, harboring a lac::luxCDABE fused plasmid, which shows lower bioluminescence levels when cellular metabolism is inhibited, was used to monitor the cellular toxicity of polycyclic aromatic hydrocarbons (PAHs). PAHs, classified as pericondensed (PCPAHs) or catacondensed (CCPAHs) according to their molecular structures, were differentiable according to the response of this biosensor. Only CCPAHs were found

Hyun Joo Lee; Julien Villaume; David C. Cullen; Byoung Chan Kim; Man Bock Gu

2003-01-01

53

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

54

Lysis of Escherichia coli by Marine Microorganisms  

Microsoft Academic Search

INVESTIGATIONS of the lethal effect of seawater on Escherichia coli, the common indicator organism for pollution by intestinal pathogens, have suggested a variety of possible mechanisms1-3. The negative effect of heat sterilization of seawater on its specific bactericidal action indicates a biological interaction which has been neither confirmed nor disproved. We attempt to define here the role of the native

R. Mitchell; Shlomit Yankofsky; H. W. JANNASCH

1967-01-01

55

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

56

Transcriptional Response of Escherichia coli to TPEN  

PubMed Central

DNA microarrays were used to probe the transcriptional response of Escherichia coli to N,N,N?,N?-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN). Fifty-five transcripts were significantly up-regulated, including all of the genes that are regulated by Zur and many that are regulated by Fur. In the same TPEN-treated cells, 46 transcripts were significantly down-regulated.

Sigdel, Tara K.; Easton, J. Allen; Crowder, Michael W.

2006-01-01

57

Escherichia coli O157 and Children  

MedlinePLUS

... toddlers who may fall down frequently. Avoid hand-to-mouth behaviors. Do not let children use pacifiers or sippy cups while in a ... shared, sold, traded, exchanged, or rented. Please refer to The JAMA Network's Privacy Policy for ... Escherichia coli O157 and Children. Arch Pediatr Adolesc Med. 2009;163(1):96. ...

58

Development of Bacteriophage in Escherichia coli B  

Microsoft Academic Search

EXAMINATION of living cultures of Salmonella typhimurium by phase-contrast illumination has revealed the presence of characteristic changes when this organism is infected with different bacteriophages1. The corresponding changes which occur in infected Escherichia coli B. have now been studied by the same method. The seven members of the `T' series of coliphages2 have been classified in terms of serological characters,

J. S. K. Boyd

1949-01-01

59

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

60

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

61

Infectious endocarditis caused by Escherichia coli.  

PubMed

Although Escherichia coli is among the most common causes of Gram-negative bacteraemia, infectious endocarditis (IE) due to this pathogen is rare. A 67-y-old male without a previous medical history presented with a new mitral regurgitation murmur and persisting E. coli bacteraemia in spite of broad-spectrum intravenous antibiotics. Transthoracic and transoesophageal echocardiography revealed a severe mitral endocarditis. E. coli DNA was identified from the mitral valve and the vegetation, and no other pathogen was found. The case was further complicated by spondylodiscitis and bilateral endophthalmitis. Extra-intestinal pathogenic E. coli (ExPEC) are able to colonize tissue outside the gastrointestinal tract and contain a variety of virulence factors that may enable the pathogens to invade and induce infections in the cardiac endothelia. In these cases echocardiography as the imaging technology is of paramount importance for the correct diagnosis and treatment. PMID:21309637

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

2011-02-10

62

FTIR nanobiosensors for Escherichia coli detection.  

PubMed

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 × 10(2) CFU/mL, constituting a simple and selective method for the effective screening of water samples. PMID:23019542

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

2012-07-03

63

Escherichia coli genosensor based on polyaniline.  

PubMed

Avidin-modified polyaniline (PANI) electrochemically deposited onto a Pt disk electrode has been utilized for direct detection of Escherichia coli by immobilizing a 5'-biotin-labeled E. coli probe (BdE) using a differential pulse voltammetric technique in the presence of methylene blue as a DNA hybridization indicator. Depending on the target sample and the sonication time, this BdE-avidin-PANI bioelectrode can be utilized to electrochemically detect a complementary target probe (0.009 ng/microL), E. coli genomic DNA (0.01 ng/microL) and 11 E. coli cells/mL in 60 s to 14 min (hybridization time) without using PCR and can be used 5-7 times at temperatures of 30-45 degrees C. PMID:17630719

Arora, Kavita; Prabhakar, Nirmal; Chand, Subhash; Malhotra, B D

2007-07-14

64

Predation of Escherichia coli by Colpoda steinii.  

PubMed Central

A study of single-stage chemostat cultures of Colpoda steinii. Escherichia coli, and glucose is reported here. Two levels of glucose were fed as the limiting nutrient to the chemostat cultures. The cultures were studied at three holding times. Oscillations developed at short holding time and damped oscillations developed a long-residence times that approached steady-state conditions of populations of C. steinii and E. coli and concentrations of glucose. The experimental data are fitted to and compared with Jost's model.

Drake, J F; Tsuchiya, H M

1976-01-01

65

Predation of Escherichia coli by Colpoda steinii.  

PubMed

A study of single-stage chemostat cultures of Colpoda steinii. Escherichia coli, and glucose is reported here. Two levels of glucose were fed as the limiting nutrient to the chemostat cultures. The cultures were studied at three holding times. Oscillations developed at short holding time and damped oscillations developed a long-residence times that approached steady-state conditions of populations of C. steinii and E. coli and concentrations of glucose. The experimental data are fitted to and compared with Jost's model. PMID:820258

Drake, J F; Tsuchiya, H M

1976-06-01

66

Escherichia coli Field Contamination of Pecan Nuts  

PubMed Central

More pecan samples collected from grazed orchards were contaminated with Escherichia coli than were samples from nongrazed orchards. No differences in frequency of contamination between mechanically and manually harvested nuts occurred. Nutmeats from whole uncracked pecans that were soaked for 24 h in a lactose broth solution containing E. coli did not become contaminated. Twentyfour percent of the whole pecans soaked in water for 48 h to simulate standing in a rain puddle developed openings along shell suture lines which did not completely close when the nuts were redried.

Marcus, Karen A.; Amling, H. J.

1973-01-01

67

Characterization Methods of a Whole-Cell Bioluminescent Biosensor  

Microsoft Academic Search

A whole-cell bioluminescent biosensor dynamics based on genetically engineered Escherichia coli bacteria carrying a promoter-reporter fusion is often determined by a series of chemical reactions such as gene expression and reactions involving protein concentrations at nanomolar volume. In this paper, we derive an anayltical model of a whole-cell bioluminescent biosensor based on the Michaelis-Menten kinetics of simple enzymatic reactions. The

Ramiz Daniel; Ronen Almog; Yosi Shacham-Diamand

2010-01-01

68

A bioluminescent sensor for high throughput toxicity classification  

Microsoft Academic Search

A high throughput toxicity monitoring and classification biosensor system has been successfully developed using four immobilized bioluminescent Escherichia coli strains, DPD2511, DPD2540, DPD2794 and TV1061, which have plasmids bearing a fusion of a specific promoter to the luxCDABE operon. The bioluminescence of DPD2511 increases in the presence of oxidative damage, DPD2540 by membrane damage, DPD2794 by DNA damage and TV1061

Byoung Chan Kim; Man Bock Gu

2003-01-01

69

Production of glycoprotein vaccines in Escherichia coli  

Microsoft Academic Search

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

Julian Ihssen; Michael Kowarik; Sandro Dilettoso; Cyril Tanner; Michael Wacker; Linda Thöny-Meyer

2010-01-01

70

Engineering the Escherichia coli Fermentative Metabolism  

Microsoft Academic Search

\\u000a 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\\u000a rapid growth. It can adapt to different growth conditions and is able to grow in the presence or absence of oxygen. Through\\u000a the use of metabolic pathway engineering and bioprocessing techniques,

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

2010-01-01

71

Intermediary Metabolite Levels in Escherichia coli  

Microsoft Academic Search

SUMMARY The intra- and extracellular concentrations of a number of phosphorylated inter- mediary metabolites in Escherichia coli were measured radiochemically during growth in low phosphate (0.75 mM) media containing (32P)Pi. Distribution studies showed that most of the monophosphate metabolites were present in the super- natant medium outside the bacteria. This was much less marked for the di- and triphosphates, and

V. MOSES; PAMELA B. SHARP

1972-01-01

72

Suppressor of phosphofructokinase mutations of Escherichia coli.  

PubMed

The known locus of fructose-6-phosphate kinase mutations (pfkA) in Escherichia coli is at 76 min on the genetic map. We have now found another gene, pfkB, at 33 min, mutation of which suppresses pfkA mutations. The suppression is not informational, and pfkB may be a second gene for fructose-6-phosphate kinase activity. PMID:4263401

Morrissey, A T; Fraenkel, D G

1972-10-01

73

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

74

Noninvasive Real-time Imaging of Tumors and Metastases Using Tumor-targeting Light-emitting Escherichia coli  

Microsoft Academic Search

Purpose  A number of bacteria types are known to preferentially grow in tumors. We have taken advantage of this phenomenon to target\\u000a luciferase-expressing Escherichia coli to tumors and metastases in mouse models to image them noninvasively.\\u000a \\u000a \\u000a \\u000a Methods and Results  After intravenous injection of pLux-expressing E. coli (108 CFU), bioluminescence signals from the bacteria were detected exclusively in tumor tissue after 24 hours.

Jung-Joon Min; Hyun-Ju Kim; Jae Hyo Park; Sungmin Moon; Jae Ho Jeong; Yeoung-Jin Hong; Kyoung-Oh Cho; Jong Hee Nam; Nacksung Kim; Young-Kyu Park; Hee-Seung Bom; Joon Haeng Rhee; Hyon E. Choy

2008-01-01

75

Action of sodium deoxycholate on Escherichia coli  

SciTech Connect

Sodium deoxycholate is used in a number of bacteriological media for the isolation and classification of gram-negative bacteria from food and the environment. Initial experiments to study the effect of deoxycholate on the growth parameters of Escherichia coli showed an increase in the lag time constant and generation time and a decrease in the growth rate constant total cell yield of this microorganisms. Cell fractionation studies indicated that sodium deoxycholate at levels used in bacteriological media interferes with the incorporation of (U-/sup 14/C)glucose into the cold-trichloroacetic acid-soluble, ethanol-soluble, and trypsin-soluble cellular fractions of E. coli. Finally, sodium deoxycholate interfered with the flagellation and motility of Proteus mirabilis and E. coli. It would appear then that further improvement of the deoxycholate medium may be in order.

D'Mello, A.; Yotis, W.W.

1987-08-01

76

DNA Ligase Mutants of Escherichia coli  

PubMed Central

A procedure is described for the isolation of Escherichia coli mutants with either excess or deficient DNA ligase activity. A mutant that overproduces DNA ligase supports the growth of ligase-defective (gene 30 mutant) T4 phages. Even T4 rII-gene 30 double mutants, which are able to grow in normal E. coli, cannot grow in cells deficient in DNA ligase. A functional DNA ligase, supplied either by the phage or the host, thus seems to be required for T4 growth. An E. coli strain that makes a temperature-sensitive DNA ligase becomes radiation-sensitive at high temperature, but otherwise grows normally and shows no obvious defect in DNA replication.

Gellert, Martin; Bullock, Minnie L.

1970-01-01

77

Comparative Resistance of 'Escherichia coli' and Enterococci to Chlorination.  

National Technical Information Service (NTIS)

Pure cultures of Escherichia coli and Enterococcus faecium were inactivated by free chlorine and monochloramine. Indigenous E. coli and enterococci in wastewater effluents were also inactivated. Selective bacteriological media specifically designed for th...

E. W. Rice T. C. Covert D. K. Wild D. Berman S. A. Johnson

1992-01-01

78

Cation Transport in Escherichia coli  

PubMed Central

Methods have been developed to study the intracellular Na and K concentrations in E. coli, strain K-12. These intracellular cation concentrations have been shown to be functions of the extracellular cation concentrations and the age of the bacterial culture. During the early logarithmic phase of growth, the intracellular K concentration greatly exceeds that of the external medium, whereas the intracellular Na concentration is lower than that of the growth medium. As the age of the culture increases, the intracellular K concentration falls and the intracellular Na concentration rises, changes which are related to the fall in the pH of the medium and to the accumulation of the products of bacterial metabolism. When stationary phase cells, which are rich in Na and poor in K, are resuspended in fresh growth medium, there is a rapid reaccumulation of K and extrusion of Na. These processes represent oppositely directed net ion movements against concentration gradients, and have been shown to be dependent upon the presence of an intact metabolic energy supply.

Schultz, Stanley G.; Solomon, A. K.

1961-01-01

79

Profiling of Escherichia coli Chromosome database.  

PubMed

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

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

2008-01-01

80

Biophysical characterization of highly active recombinant Gaussia luciferase expressed in Escherichia coli.  

PubMed

Recently, the smallest bioluminescent protein (MW: 19.9 kDa), Gaussia luciferase (GLuc), has been isolated from the marine copepod Gaussia princeps and has attracted much attention as a reporter protein. However, preparation of large quantities of homogeneous natively folded recombinant GLuc appears to be difficult due to its ten cysteines. Here, we report the biophysical characterization of recombinant GLuc expressed using a novel Escherichia coli expression system based on a cold induced expression vector (pCold). Using this system, a large fraction of the protein was expressed in the soluble fraction. GLuc, purified exclusively from the supernatant using nickel affinity chromatography, yielded a large amount of pure GLuc with a native disulfide bond pattern (Soluble-GLuc). Soluble-GLuc had a strong bioluminescence activity and it retained 65% of its activity after 30 min incubation at 95 degrees C. Soluble-GLuc remained fully folded until 40 degrees C, as assessed by circular dichroism; and the thermal denaturation curve was S-shaped, indicating a cooperative transition, with a midpoint temperature of 56 degrees C. These results indicate that both the structure and bioluminescence activity of GLuc remain stable at high temperatures, and they strongly suggest GLuc's potential as a reporter protein. PMID:20452471

Rathnayaka, Tharangani; Tawa, Minako; Sohya, Shihori; Yohda, Masafumi; Kuroda, Yutaka

2010-05-07

81

Enteroaggregative Escherichia coli Related to Uropathogenic Clonal Group A  

PubMed Central

Enteroaggregative Escherichia coli (EAEC) are heterogeneous, diarrheagenic E. coli. Of EAEC strains from Nigeria, 10 independent antimicrobial-resistant isolates belonged to the multilocus sequence type 69 clonal complex, to which uropathogenic E. coli clonal group A belongs. This finding suggests a recent common ancestor for these distinct groups of pathogenic E. coli.

Wallace-Gadsden, Faith; Johnson, James R.; Wain, John

2007-01-01

82

Antimicrobial assay optimization and validation for HTS in 384-well format using a bioluminescent E. coli K-12 strain.  

PubMed

This report describes the optimization and validation of an antimicrobial assay based on the genetically modified bacterial strain Escherichia coli K-12 (pTetlux1). The use of this particular strain enables an inducible cell-based bioluminescent assay for high-throughput screening (HTS) of antimicrobial agents, which shows a pronounced detection of compounds targeting transcriptional and translational events in protein synthesis. The optimizations in 96-well format led to several improvements in assay conditions, such as reduction of the pre-incubation time before luminescence induction by half. The threshold for DMSO tolerability was concluded to be up to 1%. Assay protocol was further miniaturized into 384-well format and the liquid handling was automated using a robotic workstation. The use of compound pre-plating into 384-well plates as a part of the process was evaluated, and the total assay volume was further downscaled from 50 ?l to 30 ?l. With this approach, the amount of test compound needed per well was reduced to nanoliter volumes. Using the miniaturized protocol a pilot screen of 2000 known drugs and bioactives was performed. The assay performance was evaluated by calculating known assay quality parameters, the Z' factor having a mean value of 0.8 during the compound library screening indicated an excellent performance. Of the assay positives, 54 compounds showed high inhibitions (60-100%), of which the majority (89%) were known antibacterial agents. Of the actives showing >60% inhibition, 16 compounds were identified as known transcriptional and translational inhibitors. The screening results demonstrated that the miniaturized assay is well suited for identification of antimicrobial compounds in HT screening, and that the assay is specifically sensitive towards bacterial transcription and translation inhibitors. PMID:23747659

Nybond, Susanna; Karp, Matti; Tammela, Päivi

2013-06-04

83

Engineering Desiccation Tolerance in Escherichia coli  

PubMed Central

Recombinant sucrose-6-phosphate synthase (SpsA) was synthesized in Escherichia coli BL21DE3 by using the spsA gene of the cyanobacterium Synechocystis sp. strain PCC 6803. Transformants exhibited a 10,000-fold increase in survival compared to wild-type cells following either freeze-drying, air drying, or desiccation over phosphorus pentoxide. The phase transition temperatures and vibration frequencies (P 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 O stretch) in phospholipids suggested that sucrose maintained membrane fluidity during cell dehydration.

Billi, Daniela; Wright, Deborah J.; Helm, Richard F.; Prickett, Todd; Potts, Malcolm; Crowe, John H.

2000-01-01

84

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

85

Transient fluorescence in synchronously dividing Escherichia coli.  

PubMed Central

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

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

1985-01-01

86

Transient fluorescence in synchronously dividing Escherichia coli.  

PubMed

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

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

1985-11-01

87

Inhibition of Escherichia coli B by Homoarginine  

PubMed Central

Homoarginine inhibits the growth of Escherichia coli B, but not of E. coli K-12. These two strains also differ in regard to repressibility of the arginine-forming enzymes. In K-12, arginine acts as a repressor whereas in B it does not. The latter difference is determined by different alleles of a regulator gene, arg R. In K-12 × B crosses, it was shown that the genetic determinant for homoarginine sensitivity is closely linked to or identical with arg R. Homoarginine-resistant mutants of B were isolated. The biochemical mechanism of homoarginine inhibition is not known. However, whether or not a strain is sensitive to homoarginine seems to depend on the intracellular level of arginine. In B this level is relatively low and inflexible as a result of the action of a repressor whose formation is determined by the B-specific allele of arg R.

Peyru, Graciela M.; Maas, Werner K.

1967-01-01

88

Determination of spatial and temporal colonization of enteropathogenic E. coli and enterohemorrhagic E. coli in mice using bioluminescent in vivo imaging  

PubMed Central

Infectious diarrhea is a major contributor of child morbidity and mortality in developing nations. Murine models to study the pathogenesis of infectious diarrhea caused by organisms such as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) are not fully characterized. More emphasis has been placed on infection of mice with the murine specific pathogen Citrobacter rodentium. While these three organisms are genetically related they are not identical. Our goal was to better characterize the murine model of EPEC and EHEC infection by using bioluminescent bacteria to determine temporal and spatial colonization of these two human pathogens. EPEC and EHEC were transformed with a bacterial luciferase expression plasmid containing the constitutive OmpC promoter. C57BL/6 mice were orally inoculated with bioluminescent EPEC or EHEC and bacterial localization in the intestine was monitored ex vivo and in vivo by IVIS. At 3 days after infection, EPEC, EHEC and Citrobacter rodentium were all localized in the cecum and colon. EPEC colonization peaked at day 2–3 and was undetectable by day 7. The bioluminescent EPEC adheres to the cecum and colon of the mouse intestine. However, when EPEC infected mice were administered xylazine/ketamine for in vivo live imaging, the EPEC persisted at high densities for up to 31 days. This is the first report of a bioluminescent imaging of luciferase expressing EPEC in a mouse model.

Rhee, Ki-Jong; Cheng, Hao; Harris, Antoneicka; Morin, Cara; Kaper, James B

2011-01-01

89

Microcins and urovirulence in Escherichia coli.  

PubMed

Urinary tract infections are among the most common infectious diseases encountered in humans and Escherichia coli is their leading etiologic agent. Uropathogenic E. coli encompasses a group of bacteria possessing a variable virulence gene assortment. It is generally agreed that many urovirulence factors remain to be discovered and that this information is required to gain knowledge on the pathogenic processes underlying the different clinical presentations of urinary tract infections. The production of higher-molecular-mass microcins, a group of ribosomally-synthesized peptide antibiotics comprising microcins H47, I47, E492, M and ColV, has been proposed as a virulence trait of some uropathogenic E. coli. To study this possibility, clones producing any of these microcins were selected from a collection of 160 Gram-negative clinical isolates from urine cultures and their virulence profile was analyzed. The study consisted in surveying genetic loci known to be relevant to urinary tract infection caused by E. coli. Depending on the type of microcin produced, different virulence patterns were observed which seemed to be determined by the degree of compatibility between virulence and microcin loci. In conclusion, results pointed to a relationship between higher-molecular-mass microcins and urovirulence. PMID:19744552

Azpiroz, María F; Poey, María Eloisa; Laviña, Magela

2009-09-08

90

Natural DNA uptake by Escherichia coli.  

PubMed

Escherichia coli has homologues of the competence genes other species use for DNA uptake and processing, but natural competence and transformation have never been detected. Although we previously showed that these genes are induced by the competence regulator Sxy as in other gamma-proteobacteria, no conditions are known that naturally induce sxy expression. We have now tested whether the competence gene homologues encode a functional DNA uptake machinery and whether DNA uptake leads to recombination, by investigating the effects of plasmid-borne sxy expression on natural competence in a wide variety of E. coli strains. High- and low-level sxy expression alone did not induce transformation in any of the strains tested, despite varying the transforming DNA, its concentration, and the incubation conditions used. Direct measurements of uptake of radiolabelled DNA were below the limit of detection, however transformants were readily detected when recombination functions were provided by the lambda Red recombinase. This is the first demonstration that E. coli sxy expression can induce natural DNA uptake and that E. coli's competence genes do encode a functional uptake machinery. However, the amount of transformation cells undergo is limited both by low levels of DNA uptake and by inefficient DNA processing/recombination. PMID:22532864

Sinha, Sunita; Redfield, Rosemary J

2012-04-19

91

Generation of a restriction minus enteropathogenic Escherichia coli E2348\\/69 strain that is efficiently transformed with large, low copy plasmids  

Microsoft Academic Search

BACKGROUND: Many microbes possess restriction-modification systems that protect them from parasitic DNA molecules. Unfortunately, the presence of a restriction-modification system in a given microbe also hampers genetic analysis. Although plasmids can be successfully conjugated into the enteropathogenic Escherichia coli strain E2348\\/69 and optimized protocols for competent cell preparation have been developed, we found that a large, low copy (~15) bioluminescent

Neil Hobson; Nancy L Price; Jordan D Ward; Tracy L Raivio

2008-01-01

92

[Frequency of Escherichia coli resistance in Switzerland].  

PubMed

Monitoring the drug resistance of bacteria is necessary at regional, national and international levels. Over a two-week period in October 1978, 2561 strains of Escherichia coli and coliforms were isolated from stool specimens obtained from 19 civilian institutions (1338 strains) and from 9 army training camps (1223 strains) located all over Switzerland. Only a few of the donors had undergone recent antimicrobial therapy. The bacterial strains were rapidly distributed among 7 Swiss army microbiological field laboratories and tested for resistance against ampicillin, gentamycin, tetracycline and cotrimoxazole by standard disc diffusion techniques. Criteria for the interpretation of inhibition zones were adapted from WHO and NCCLS guidelines. E. coli ATCC 25922 served as a control strain. The overall resistance rates of E. coli and coliforms were 18% for ampicillin, 0.3% for gentamycin, 33% for tetracycline and 4% for cotrimoxazole. Multiple drug resistance patterns involving these four drugs plus sulfisoxazole, streptomycin, kanamycin, chloramphenicol, cefalothin and colistin were analyzed. Many combinations of drug resistances occurred in far higher numbers than was expected from individual drug resistance frequencies, a fact which suggested linkage of resistance genes. The resistance frequencies observed were shown by several tests of reproducibility to be subject to a modest overall error of approximately 20%. PMID:7022622

Braun, R; Fitzi, K; Gutzwiller, F; Hohl, H R; van der Linde, F; Gelzer, J

1981-07-01

93

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

94

Inactivation of Escherichia coli with ozone: chemical and inactivation kinetics  

Microsoft Academic Search

The apparent chemical and inactivation reactions taking place during the disinfection of Escherichia coli with ozone in the presence of humic acid were investigated with continuous-flow tubular reactors. The apparent decomposition of dissolved ozone in the presence of humic acid and E. coli cells was modeled successfully with mixed second-order rate expressions within a time scale relevant to E. coli

Nimrata K Hunt; Benito J Mariñas

1999-01-01

95

Escherichia coli resistance to quinolones at a comprehensive cancer center  

Microsoft Academic Search

As part of Meropenem Yearly Susceptibility Test Information Collection\\/USA Surveillance Programme, we monitored the occurrence of quinolone resistance in Escherichia coli over a 10-year period. A total of 271 E. coli isolates from our institution were tested over a 10-year period. Screening for quinolone resistance (qnr) gene was performed. A decline in susceptibility of E. coli isolates to quinolones and

Coralia N. Mihu; Paul R. Rhomberg; Ronald N. Jones; Elizabeth Coyle; Randall A. Prince; Kenneth V. Rolston

2010-01-01

96

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

97

Risk factors of ciprofloxacin resistance in urinary Escherichia coli isolates  

Microsoft Academic Search

Background and Purpose: Increasing rates of fluoroquinolone resistance among Escherichia coli have been reported in Taiwan and worldwide. We aimed to identify the risk factors of ciprofloxacin resistance in urinary E. coli isolates. Methods: Patients with positive urine culture result for E. coli and resistance to ciprofloxacin between Septem- ber 1, 1999 and December 31, 1999 were prospectively identified as

Chun-Yu Lin; Shu-Hua Huang; Tun-Chieh Chen; Po-Liang Lu; Wei-Ru Lin; Yen-Hsu Chen

2008-01-01

98

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

99

Indole transport across Escherichia coli membranes.  

PubMed

Indole has many, diverse roles in bacterial signaling. It regulates the transition from exponential to stationary phase, it is involved in the control of plasmid stability, and it influences biofilm formation, virulence, and stress responses (including antibiotic resistance). Its role is not restricted to bacteria, and recently it has been shown to include mutually beneficial signaling between enteric bacteria and their mammalian hosts. In many respects indole behaves like the signaling component of a quorum-sensing system. Indole synthesized within the producer bacterium is exported into the surroundings where its accumulation is detected by sensitive cells. A view often repeated in the literature is that in Escherichia coli the AcrEF-TolC and Mtr transporter proteins are involved in the export and import, respectively, of indole. However, the evidence for their involvement is indirect, and it has been known for a long time that indole can pass directly through a lipid bilayer. We have combined in vivo and in vitro approaches to examine the relative importance of protein-mediated transport and direct passage across the E. coli membrane. We conclude that the movement of indole across the E. coli membrane under normal physiological conditions is independent of AcrEF-TolC and Mtr. Furthermore, direct observation of individual liposomes shows that indole can rapidly cross an E. coli lipid membrane without the aid of any proteinaceous transporter. These observations not only enhance our understanding of indole signaling in bacteria but also provide a simple explanation for the ability of indole to signal between biological kingdoms. PMID:21296966

Piñero-Fernandez, S; Chimerel, C; Keyser, U F; Summers, D K

2011-02-04

100

Indole Transport across Escherichia coli Membranes ?  

PubMed Central

Indole has many, diverse roles in bacterial signaling. It regulates the transition from exponential to stationary phase, it is involved in the control of plasmid stability, and it influences biofilm formation, virulence, and stress responses (including antibiotic resistance). Its role is not restricted to bacteria, and recently it has been shown to include mutually beneficial signaling between enteric bacteria and their mammalian hosts. In many respects indole behaves like the signaling component of a quorum-sensing system. Indole synthesized within the producer bacterium is exported into the surroundings where its accumulation is detected by sensitive cells. A view often repeated in the literature is that in Escherichia coli the AcrEF-TolC and Mtr transporter proteins are involved in the export and import, respectively, of indole. However, the evidence for their involvement is indirect, and it has been known for a long time that indole can pass directly through a lipid bilayer. We have combined in vivo and in vitro approaches to examine the relative importance of protein-mediated transport and direct passage across the E. coli membrane. We conclude that the movement of indole across the E. coli membrane under normal physiological conditions is independent of AcrEF-TolC and Mtr. Furthermore, direct observation of individual liposomes shows that indole can rapidly cross an E. coli lipid membrane without the aid of any proteinaceous transporter. These observations not only enhance our understanding of indole signaling in bacteria but also provide a simple explanation for the ability of indole to signal between biological kingdoms.

Pinero-Fernandez, S.; Chimerel, C.; Keyser, U. F.; Summers, D. K.

2011-01-01

101

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

102

Bioluminescent signal system: bioluminescence immunoassay of pathogenic organisms.  

PubMed

The Ca(2+)-regulated photoprotein obelin has been examined as a label for bioluminescence immunoassay of infective agents. The hepatitis B virus (HbsAg) and the bacteria Escherichia coli and Shigella sonnei lipopolysaccharide (LPS) were chosen as model antigens. Chemically synthesized obelin-corresponding antibody conjugates were used in a solid-phase microplate immunoassay. The sensitivities achieved by the assay were 0.25 ng/mL for S. sonnei LPS and 0.375 ng/mL for HbsAg. A novel, filter-based immunoassay to determine bacterial admixtures in the environment was proposed. The NanoCeram filters were effectively applied to 'trap' and pre-concentrate pathogens from samples under study for the purposes of further detection and measurement of the absorbed material by bioluminescence immunoassay. PMID:17286244

Frank, L; Markova, S; Remmel, N; Vysotski, E; Gitelson, I

103

Mutations Affecting Iron Transport in Escherichia coli  

PubMed Central

A mutant of Escherichia coli K-12 unable to form an essential component of the enterochelin-dependent iron transport system has been isolated. This strain carries a mutation in a gene designated fep, mapping close to two genes, entA and entD, concerned with enterochelin synthesis. Strain AN102, which carries the fep? allele, accumulates large quantities of enterochelin and gives a growth response to sodium citrate. The cytochrome b1 and total iron content, and the measurement of the uptake of 55Fe3+, indicate an impairment of the enterochelin-dependent iron transport system. The growth response to sodium citrate is related to the presence, in strain AN102, of an inducible citrate-dependent iron transport system. Images

Cox, G. B.; Gibson, F.; Luke, R. K. J.; Newton, N. A.; O'Brien, I. G.; Rosenberg, H.

1970-01-01

104

Ribonuclease Sensitivity of Escherichia coli Ribosomes  

PubMed Central

Santer, Melvin (Haverford College, Haverford, Pa.), and Josephine R. Smith. Ribonuclease sensitivity of Escherichia coli ribosomes. J. Bacteriol. 92:1099–1110. 1966.—The ribonucleic acid (RNA) contained in 70S ribosomes and in 50S and 30S subunits was hydrolyzed by pancreatic ribonuclease. A 7% amount of the RNA was removed from the 70S particle; at 10?4m magnesium concentration, a maximum of 24 and 30% of the RNA in the 50S and the 30S fractions, respectively, was removed by ribonuclease. At the two lower magnesium ion concentrations, 50S ribosomes did not lose any protein, whereas 30S ribosomes lost protein as a result of ribonuclease treatment. A number of proteins were removed from the 30S particles by ribonuclease, and these proteins were antigenically related to proteins present in 50S ribosomes. The differential effect of ribonuclease on 50S and 30S ribosomes suggested that they have structural dissimilarities. Images

Santer, Melvin; Smith, Josephine R.

1966-01-01

105

l-Serine Deaminase of Escherichia coli  

PubMed Central

The native l-serine deaminase (l-serine hydrolyase, deaminating, EC 4.2.1.13) of Escherichia coli K-12, which seems to be a very labile protein, is rather stable in concentrated solution. Dilution rapidly inactivates it, but in the presence of a saturating concentration of l-serine the molecule is protected from inactivation. It is a very specific enzyme; l-serine is the sole substrate with a Km value of 6.60 × 10?3m. d-Serine and l-cysteine are competitive inhibitors. Substrate saturation curves of the native enzyme show sigmoid shape, whereas the enzyme liberated from the bacteria in the presence of l-serine exhibits normal Michaelis-Menten kinetics.

Alfoldi, Lajos; Rasko, Istvan; Kerekes, Erzsebet

1968-01-01

106

Direct upstream motility in Escherichia coli.  

PubMed

We provide an experimental demonstration of positive rheotaxis (rapid and continuous upstream motility) in wild-type Escherichia coli freely swimming over a surface. This hydrodynamic phenomenon is dominant below a critical shear rate and robust against Brownian motion and cell tumbling. We deduce that individual bacteria entering a flow system can rapidly migrate upstream (>20 ?m/s) much faster than a gradually advancing biofilm. Given a bacterial population with a distribution of sizes and swim speeds, local shear rate near the surface determines the dominant hydrodynamic mode for motility, i.e., circular or random trajectories for low shear rates, positive rheotaxis for moderate flow, and sideways swimming at higher shear rates. Faster swimmers can move upstream more rapidly and at higher shear rates, as expected. Interestingly, we also find on average that both swim speed and upstream motility are independent of cell aspect ratio. PMID:22500751

Kaya, Tolga; Koser, Hur

2012-04-03

107

Anaerobic iron uptake by Escherichia coli.  

PubMed Central

Assimilation and uptake of iron in anaerobic cultures of Escherichia coli were supported by iron supplied as ferrienterobactin, ferrichrome, and ferrous ascorbate; however, as in the aerobic cultures, ferrichrome A was a poor iron source. Albomycin inhibited both aerobically and anaerobically grown cells. The siderophore outer membrane receptor proteins FepA and FhuA were produced under anaerobic iron-deficient conditions. Anaerobic transport of ferrienterobactin and ferrichrome was inhibited by KCN and dinitrophenol. The Km for ferrienterobactin uptake in anaerobically grown cells was 0.8 microM, and the Vmax was 38 pmol/min per mg, compared with 0.1 microM and 80 pmol/min per mg, respectively, in aerobically grown cells.

Lodge, J S; Emery, T

1984-01-01

108

Phosphoglucomutase Mutants of Escherichia coli K-12  

PubMed Central

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

Adhya, Sankar; Schwartz, Maxime

1971-01-01

109

Direct Upstream Motility in Escherichia coli  

PubMed Central

We provide an experimental demonstration of positive rheotaxis (rapid and continuous upstream motility) in wild-type Escherichia coli freely swimming over a surface. This hydrodynamic phenomenon is dominant below a critical shear rate and robust against Brownian motion and cell tumbling. We deduce that individual bacteria entering a flow system can rapidly migrate upstream (>20 ?m/s) much faster than a gradually advancing biofilm. Given a bacterial population with a distribution of sizes and swim speeds, local shear rate near the surface determines the dominant hydrodynamic mode for motility, i.e., circular or random trajectories for low shear rates, positive rheotaxis for moderate flow, and sideways swimming at higher shear rates. Faster swimmers can move upstream more rapidly and at higher shear rates, as expected. Interestingly, we also find on average that both swim speed and upstream motility are independent of cell aspect ratio.

Kaya, Tolga; Koser, Hur

2012-01-01

110

Enzymatic properties of Escherichia coli peptide deformylase.  

PubMed Central

Since its discovery in crude extracts in the late sixties, Escherichia coli peptide deformylase activity could not be further characterized because of an apparent extreme instability. We show that this behavior was caused by an inadequate activity assay, involving substrate concentration inhibition and substrate precipitation in crude extracts. The homogeneous protein, as it was previously purified (T. Meinnel and S. Blanquet J. Bacteriol. 175:7737-7740, 1993), had actually retained its initial activity. The influence on the deformylation reaction of several factors was studied and used to improve the activity assay. Pure peptide deformylase proves to act only on peptide substrates with an N-formylmethionyl moiety. In agreement with the occurrence of zinc in the enzyme, peptide deformylase activity is inhibited by 1,10-phenanthroline.

Meinnel, T; Blanquet, S

1995-01-01

111

Aerobic TMAO respiration in Escherichia coli.  

PubMed

In the absence of oxygen, Escherichia coli can use alternative exogenous electron acceptors, including trimethylamine oxide (TMAO), to generate energy. In this study, we showed that in contrast to the other anaerobic respiratory systems, the TMAO reductase (Tor) system was expressed during both aerobiosis and anaerobiosis. By using a torA-lacZ fusion and quantitative reverse transcription polymerase chain reaction, we established that the torCAD operon encoding the Tor system was induced in the presence of TMAO mainly during exponential phase, and that optimal induction required a certain level of DNA supercoiling. We also showed that the presence of oxygen prevented neither the biogenesis of the Tor system nor the reduction of TMAO. The physiological role of TMAO reduction during aerobiosis has not been yet established, but our experiments suggest that alkaline TMA production could enhance the growth conditions by increasing the pH of the culture. PMID:17850256

Ansaldi, Mireille; Théraulaz, Laurence; Baraquet, Claudine; Panis, Gaël; Méjean, Vincent

2007-09-10

112

Dispensability of Escherichia coli's latent pathways  

PubMed Central

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

Cornelius, Sean P.; Lee, Joo Sang; Motter, Adilson E.

2011-01-01

113

A bioluminescence-based assay for enumeration of lytic bacteriophage.  

PubMed

A bioluminescence-based assay for enumeration of lytic bacteriophage was developed. The assay consists of a bioluminescent Escherichia coli as the host bacterium, the lytic bacteriophage T4 and an automated luminometer measuring luminescence over time. The assay is based on the decrease in luminescence as the bioluminescent host cells are lysed by T4. The T4 concentration, bioluminescent E. coli concentration, phage suspension medium, and temperature (25 degrees C and 37 degrees C) were varied. There was a strong negative correlation between bioluminescence intensities and T4 phage concentrations at both room temperature (R(2)=0.993) and 37 degrees C (R(2)=0.970). Phage was detected more rapidly at 37 degrees C than at 25 degrees C. The detection limit was also lower when the assay was performed at 37 degrees C with a minimum detection level of 2.4 log CFU/ml compared to 3.4 log CFU/ml for 25 degrees C. The assay was used to determine thermal inactivation using T4 phages heated at 70 degrees C for 0 to 30 min, and phage concentrations were determined using the bioluminescence assay and a standard plaque assay. There was no significant difference between the two enumeration methods (P>0.01). This study suggests the bioluminescence-based assay can be used as an alternative for quantitatively monitoring phage infectivity, instead of conventional standard plaque assays. PMID:19628012

Kim, S; Schuler, B; Terekhov, A; Auer, J; Mauer, L J; Perry, L; Applegate, B

2009-07-21

114

Tuning Escherichia coli for membrane protein overexpression.  

PubMed

A simple generic method for optimizing membrane protein overexpression in Escherichia coli is still lacking. We have studied the physiological response of the widely used "Walker strains" C41(DE3) and C43(DE3), which are derived from BL21(DE3), to membrane protein overexpression. For unknown reasons, overexpression of many membrane proteins in these strains is hardly toxic, often resulting in high overexpression yields. By using a combination of physiological, proteomic, and genetic techniques we have shown that mutations in the lacUV5 promoter governing expression of T7 RNA polymerase are key to the improved membrane protein overexpression characteristics of the Walker strains. Based on this observation, we have engineered a derivative strain of E. coli BL21(DE3), termed Lemo21(DE3), in which the activity of the T7 RNA polymerase can be precisely controlled by its natural inhibitor T7 lysozyme (T7Lys). Lemo21(DE3) is tunable for membrane protein overexpression and conveniently allows optimizing overexpression of any given membrane protein by using only a single strain rather than a multitude of different strains. The generality and simplicity of our approach make it ideal for high-throughput applications. PMID:18796603

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

2008-09-16

115

Peptidase-deficient mutants of Escherichia coli.  

PubMed

Mutant derivatives of Escherichia coli K-12 deficient in several peptidases have been obtained. Mutants lacking a naphthylamidase, peptidase N, were isolated by screening for colonies unable to hydrolyze L-alanine beta-naphthylamide. Other mutants were isolated using positive selections for resistance to valine peptides. Mutants lacking peptidase A, a broad-specificity aminopeptidase, were obtained by selection for resistance to L-valyl-L-leucine amide. Mutants lacking a dipeptidase, peptidase D, were isolated from a pepN pepA strain by selection for resistance to L-valyl-glycine. Starting with a pepN pepA pepD strain, selection for resistance to L-valyl-glycyl-glycine or several other valine peptides produced mutants deficient in another aminopeptidase, peptidase B. Mutants resistant to L-valyl-L-proline lack peptidase Q, an activity capable of rapid hydrolysis of X-proline dipeptides. Using these selection procedures, a strain (CM89) lacking five different peptidases has been isolated. Although still sensitive to valine, this strain is resistant to a variety of valine di- and tripeptides. The ability of this strain to use peptides as sources of amino acids is much more restricted than that of wild-type E. coli strains. Strains containing only one of the five peptidases missing in CM89 have been constructed by transduction. The peptide utilization profiles of these strains show that each of the five peptidases can function during growth in the catabolism of peptides. PMID:355237

Miller, C G; Schwartz, G

1978-08-01

116

Peptidase-deficient mutants of Escherichia coli.  

PubMed Central

Mutant derivatives of Escherichia coli K-12 deficient in several peptidases have been obtained. Mutants lacking a naphthylamidase, peptidase N, were isolated by screening for colonies unable to hydrolyze L-alanine beta-naphthylamide. Other mutants were isolated using positive selections for resistance to valine peptides. Mutants lacking peptidase A, a broad-specificity aminopeptidase, were obtained by selection for resistance to L-valyl-L-leucine amide. Mutants lacking a dipeptidase, peptidase D, were isolated from a pepN pepA strain by selection for resistance to L-valyl-glycine. Starting with a pepN pepA pepD strain, selection for resistance to L-valyl-glycyl-glycine or several other valine peptides produced mutants deficient in another aminopeptidase, peptidase B. Mutants resistant to L-valyl-L-proline lack peptidase Q, an activity capable of rapid hydrolysis of X-proline dipeptides. Using these selection procedures, a strain (CM89) lacking five different peptidases has been isolated. Although still sensitive to valine, this strain is resistant to a variety of valine di- and tripeptides. The ability of this strain to use peptides as sources of amino acids is much more restricted than that of wild-type E. coli strains. Strains containing only one of the five peptidases missing in CM89 have been constructed by transduction. The peptide utilization profiles of these strains show that each of the five peptidases can function during growth in the catabolism of peptides. Images

Miller, C G; Schwartz, G

1978-01-01

117

Genes under positive selection in Escherichia coli  

PubMed Central

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

Petersen, Lise; Bollback, Jonathan P.; Dimmic, Matt; Hubisz, Melissa; Nielsen, Rasmus

2007-01-01

118

Biosynthesis of ethylene glycol in Escherichia coli.  

PubMed

Ethylene glycol (EG) is an important platform chemical with steadily expanding global demand. Its commercial production is currently limited to fossil resources; no biosynthesis route has been delineated. Herein, a biosynthesis route for EG production from D-xylose is reported. This route consists of four steps: D-xylose???D-xylonate???2-dehydro-3-deoxy-D-pentonate???glycoaldehyde???EG. Respective enzymes, D-xylose dehydrogenase, D-xylonate dehydratase, 2-dehydro-3-deoxy-D-pentonate aldolase, and glycoaldehyde reductase, were assembled. The route was implemented in a metabolically engineered Escherichia coli, in which the D-xylose???D-xylulose reaction was prevented by disrupting the D-xylose isomerase gene. The most efficient construct produced 11.7 g?L(-1) of EG from 40.0 g?L(-1) of D-xylose. Glycolate is a carbon-competing by-product during EG production in E. coli; blockage of glycoaldehyde???glycolate reaction was also performed by disrupting the gene encoding aldehyde dehydrogenase, but from this approach, EG productivity was not improved but rather led to D-xylonate accumulation. To channel more carbon flux towards EG than the glycolate pathway, further systematic metabolic engineering and fermentation optimization studies are still required to improve EG productivity. PMID:23233208

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

2012-12-12

119

5-Aminolevulinic acid synthesis in Escherichia coli.  

PubMed Central

A hemA mutant of Escherichia coli containing a multicopy plasmid which complemented the mutation excreted 5-aminolevulinic acid (ALA) into the medium. [1-14C]glutamate was substantially incorporated into ALA by this strain, whereas [2-14C]glycine was not. Periodate degradation of labeled ALA showed that C-5 of ALA was derived from C-1 of glutamate. The synthesis of ALA by two sonicate fractions which had been processed by gel filtration and dialysis, respectively, was dependent on glutamate, ATP, NADPH, tRNA(Glu), and pyridoxal phosphate. tRNA(Glu) stimulated ALA synthesis in a concentration-dependent manner. Pretreatment with RNase reduced this stimulation. The amino acid sequence of the cloned insert, derived from the nucleotide sequence (J.-M. Li, C. S. Russell, and S. D. Cosloy, J. Cell Biol. 107:617a, 1988), showed no homology with any ALA synthase sequenced to date. These results suggest that E. coli synthesizes ALA by the C5 pathway from the intact five-carbon chain of glutamate.

Li, J M; Brathwaite, O; Cosloy, S D; Russell, C S

1989-01-01

120

Nucleotide excision repair in Escherichia coli.  

PubMed Central

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

Van Houten, B

1990-01-01

121

PfkA locus of Escherichia coli.  

PubMed

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

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

1975-06-01

122

Indole enhances acid resistance in Escherichia coli.  

PubMed

As a stationary-phase signal, indole is secreted in large quantities by Escherichia coli on enriched media and has been shown to control several genes; however, its impact on acid resistance remains to be studied in detail. Real-time quantitative reverse transcription-polymerase chain reaction analysis revealed that indole increases the expression of the glutamine decarboxylase system that includes genes such as gadA, gadB, and gadC genes with no effect on the expression of other acid resistance systems such as arginine decarboxylase (adiA) and lysine decarboxylase (cadA, cadB, cadC, and ldcC). Indole also induces yhiE (gadE) that encodes the regulator required for expression of gadA, gadB, and gadC. These results suggest that indole enhances the survival of E. coli under acidic conditions by increasing the expression of acid resistance genes of the glutamine decarboxylase system, thus increasing its acid resistance. PMID:20470880

Hirakawa, Hidetada; Hayashi-Nishino, Mitsuko; Yamaguchi, Akihito; Nishino, Kunihiko

2010-05-12

123

Identification of pseudouridine methyltransferase in Escherichia coli  

PubMed Central

In ribosomal RNA, modified nucleosides are found in functionally important regions, but their function is obscure. Stem–loop 69 of Escherichia coli 23S rRNA contains three modified nucleosides: pseudouridines at positions 1911 and 1917, and N3 methyl-pseudouridine (m3?) at position 1915. The gene for pseudouridine methyltransferase was previously not known. We identified E. coli protein YbeA as the methyltransferase methylating ?1915 in 23S rRNA. The E. coli ybeA gene deletion strain lacks the N3 methylation at position 1915 of 23S rRNA as revealed by primer extension and nucleoside analysis by HPLC. Methylation at position 1915 is restored in the ybeA deletion strain when recombinant YbeA protein is expressed from a plasmid. In addition, we show that purified YbeA protein is able to methylate pseudouridine in vitro using 70S ribosomes but not 50S subunits from the ybeA deletion strain as substrate. Pseudouridine is the preferred substrate as revealed by the inability of YbeA to methylate uridine at position 1915. This shows that YbeA is acting at the final stage during ribosome assembly, probably during translation initiation. Hereby, we propose to rename the YbeA protein to RlmH according to uniform nomenclature of RNA methyltransferases. RlmH belongs to the SPOUT superfamily of methyltransferases. RlmH was found to be well conserved in bacteria, and the gene is present in plant and in several archaeal genomes. RlmH is the first pseudouridine specific methyltransferase identified so far and is likely to be the only one existing in bacteria, as m3?1915 is the only methylated pseudouridine in bacteria described to date.

Ero, Rya; Peil, Lauri; Liiv, Aivar; Remme, Jaanus

2008-01-01

124

Frequency of enterovirulent Escherichia coli in diarrhoeal disease in The Netherlands  

Microsoft Academic Search

To assess the role of enterovirulentEscherichia coli in The Netherlands, faecal samples of 279 patients (108 children, 171 adults) with diarrhoea and 100 healthy controls were investigated in a prospective study. EnterovirulentEscherichia coli were identified by hybridization with five different non-radioactively labelled DNA probes specific for enteropathogenicEscherichia coli (EPEC), verocytotoxin producingEscherichia coli (VTEC) and enterotoxigenicEscherichia coli (ETEC). The rate of

C. M. A. Rademaker; A. C. Fluit; M. Jansze; W. H. Jansen; J. H. Glerum; J. Verhoef

1993-01-01

125

Improvements In Ethanologenic Escherichia Coli and Klebsiella Oxytoca. (Final Report).  

National Technical Information Service (NTIS)

The current Verenium cellulosic ethanol process is based on the dilute-acid pretreatment of a biomass feedstock, followed by a two-stage fermentation of the pentose sugar-containing hydrolysate by a genetically modified ethanologenic Escherichia coli stra...

D. Nunn

2010-01-01

126

Structure Stabilization in Escherichia Coli Transfer Ribonucleic Acid.  

National Technical Information Service (NTIS)

Formaldehyde treatment of Escherichia coli B transfer ribonucleic acid (tRNA) appreciably changes hydrodynamic and optical properties. The increase in intrinsic viscosity, decrease in sedimentation coefficient coupled with the change in absorbance melting...

D. B. Millar M. MacKenzie

1967-01-01

127

76 FR 58157 - Shiga Toxin-Producing Escherichia coli  

Federal Register 2010, 2011, 2012, 2013

...Escherichia coli in Certain Raw Beef Products AGENCY: Food Safety and Inspection Service...documented, particularly in daycare settings and nursing homes, where there...In addition, FSIS will...for-cause food safety assessment...

2011-09-20

128

Effects of Protease Inhibitors on Protein Breakdown in 'Escherichia coli'.  

National Technical Information Service (NTIS)

In an attempt to learn more about the proteolytic enzymes responsible for protein turnover in cells, the effects of various protease inhibitors on protein catabolism in Escherichia coli were examined. Diisopropyl fluorophosphate, phenylmethane sulfonyl fl...

W. F. Prouty A. L. Goldberg

1971-01-01

129

Analytical strategies for improving the robustness and reproducibility of bioluminescent microbial bioreporters  

Microsoft Academic Search

Whole-cell bioluminescent (BL) bioreporter technology is a useful analytical tool for developing biosensors for environmental\\u000a toxicology and preclinical studies. However, when applied to real samples, several methodological problems prevent it from\\u000a being widely used. Here, we propose a methodological approach for improving its analytical performance with complex matrix.\\u000a We developed bioluminescent Escherichia coli and Saccharomyces cerevisiae bioreporters for copper ion

Aldo Roda; Barbara Roda; Luca Cevenini; Elisa Michelini; Laura Mezzanotte; Pierluigi Reschiglian; Kaisa Hakkila; Marko Virta

2011-01-01

130

Infected hepatic Echinococcus cyst presenting as recurrent Escherichia coli empyema.  

PubMed

An 81-year-old man, previously a shepherd in Italy, presented with recurrent Escherichia coli empyema over an 8-month period. His empyema was caused by an infected, nonviable hepatic Echinococcus cyst that eroded the diaphragm and led to intermittent spillage and pleural seeding. This case demonstrates that when dealing with Escherichia coli empyema, a subdiaphragmatic source ought to be suspected, and among immigrants from areas with prevalent hydatid disease, infected hepatic Echinococcus cyst might rarely be the cause. PMID:8452451

Chang, R; Higgins, M; DiLisio, R; Hawasli, A; Camaro, L G; Khatib, R

1993-03-01

131

Polymorphisms in the umuDC region of Escherichia species. [Escherichia coli; Escherichia alkalescens; Escherichia dispar; Escherichia aurescens  

SciTech Connect

The umuDC operon of Escherichia coli encodes mutagenic DNA repair. The umuDC regions of multiple isolates of E. coli, E. alkalescens, and E. dispar and a single stock of E. aurescens were mapped by nucleotide hybridization. umuDC is located at one end of a conserved tract of restriction endonuclease sites either 12.5 or 14 kilobase pairs long. Rearrangements, including possible deletions, were seen in the polymorphic DNA flanking the conserved tract. Restriction site polymorphisms were not found around the DNA repair gene recA or polA. The junctions of the conserved region contain direct repeats of nucleotide sequences resembling the termini of the Tn3 group of transposons. Possible mechanisms for the generation of these variants are discussed.

Sedgwick, S.G.; Robson, M.; Malik, F.

1988-04-01

132

Incidence of colicinogenic strains among human Escherichia coli.  

PubMed

During the years 1993-1999, altogether 1,043 Escherichia coli strains from colons of different persons were screened for colicinogeny using a most susceptible procedure and indicator system. In control persons (with healthy colons), 41.37% producers of colicins were found. In patients suffering from salmonelloses, the proportion of colicinogenic Escherichia coli was the same. In patients with non-specific inflammatory colon diseases, the proportion of colicinogenic Escherichia coli strains appeared slightly though weakly, significantly or unsignificantly increased: to 47.50% in morbus Crohn and to 56.10% in colitis ulcerosa. These results suggest some sort of engagement of colicinogeny in the pathogenesis thereof. In malignant tumours of the colon, the incidence of colicinogenic Escherichia coli was not altered (40.58%). This does not indicate any colicin participation in the pathology of malignant tumours. In colitis ulcerosa, the incidence of colicinogenic Escherichia coli strains inhibiting Shigella sonei 17 (the indicator for colicin Js which generally inhibits interoinvasive strains of both species) increased from 21.94% (control samples) to 41.46%. Uropathogenic Escherichia coli strains shared the same incidence of colicinogeny as controls (42.08%), if they were not haemolytic; haemolytic ones were colicinogenic with only 22.37%. This difference was highly significant. The patterns of some colicin activities in the set of five indicator strains used suggested that several wild strains produced new, so far unknown types of colicins and/or combinations thereof. PMID:11802547

Smarda, J; Obdrzálek, V

2001-01-01

133

The Asymptomatic Bacteriuria Escherichia coli Strain 83972 Outcompetes Uropathogenic E. coli Strains in Human Urine  

Microsoft Academic Search

Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract. The prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically

Viktoria Roos; Glen C. Ulett; Mark A. Schembri; Per Klemm

2006-01-01

134

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

135

EFFECT OF MANURE ON ESCHERICHIA COLI ATTACHMENT TO SOIL FRACTIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli are commonly used as indicators of fecal contamination in the environment. Attachment of bacteria to soil and sediment is an important retardation factor of bacterial transport with runoff water. Despite the fact that E. coli are derived exclusively from feces/manure, the effect of ...

136

RAPID GLUTAMATE DECARBOXYLASE ASSAY FOR THE DETECTION OF ESCHERICHIA COLI  

EPA Science Inventory

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

137

Reduction of Aerobic Acetate Production by Escherichia coli  

Microsoft Academic Search

Acetate excretion by Escherichia coli during aerobic growth on glucose is a major obstacle to enhanced recombinant protein production. We report here that the fraction of carbon flux through the anaplerotic pathways is one of the factors influencing acetate excretion. Flux analysis of E. coli central metabolic pathways predicts that increasing the fraction of carbon flux through the phosphoenolpyruvate carboxylase

William R. Farmer; James C. Liao

1997-01-01

138

Relationship among fecal coliforms and Escherichia coli in various foods  

Microsoft Academic Search

For much of the twentieth century, coliform bacteria and especially Escherichia coli have been used as indicators of possible post-processing contamination and the presence of E. coli as an indicator of fecal contamination in foods. In this study, 500 foods in 10 different groups, mainly dairy products, delicatessen products, salads, spices, cream cakes and fresh fruit and vegetable samples, were

Hilal B. Do?an-Halkman; ?brahim Çak?r; Fikret Keven; Randy W. Worobo; A. Kadir Halkman

2003-01-01

139

Genome Sequence of Enterohemorrhagic Escherichia coli NCCP15658  

PubMed Central

Enterohemorrhagic Escherichia coli causes severe food-borne disease in the guts of humans and animals. Here, we report the high-quality draft genome sequence of E. coli NCCP15658 isolated from a patient in the Republic of Korea. Its genome size was determined to be 5.46 Mb, and its genomic features, including genes encoding virulence factors, were analyzed.

Song, Ju Yeon; Yoo, Ran Hee; Jang, Song Yee; Seong, Won-Keun; Kim, Seon-Young; Jeong, Haeyoung; Kang, Sung Gyun; Kim, Byung Kwon; Kwon, Soon-Kyeong; Lee, Choong Hoon; Yu, Dong Su; Park, Mi-Sun

2012-01-01

140

Interaction of Escherichia coli and Soil Particles in Runoff  

Microsoft Academic Search

A laboratory-scale model system was developed to investigate the transport mechanisms involved in the horizontal movement of bacteria in overland flow across saturated soils. A suspension of Escherichia coli and bromide tracer was added to the model system, and the bromide concentration and number of attached and unattached E. coli cells in the overland flow were measured over time. Analysis

Richard William Muirhead; Robert Peter Collins; Philip James Bremer

2006-01-01

141

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

142

Enterotoxigenic Escherichia coli Multilocus Sequence Types in Guatemala and Mexico  

PubMed Central

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

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

2010-01-01

143

Repair System for Noncanonical Purines in Escherichia coli  

Microsoft Academic Search

Exposure of Escherichia coli strains deficient in molybdopterin biosynthesis (moa) to the purine base N-6-hydroxylaminopurine (HAP) is mutagenic and toxic. We show that moa mutants exposed to HAP also exhibit elevated mutagenesis, a hyperrecombination phenotype, and increased SOS induction. The E. coli rdgB gene encodes a protein homologous to a deoxyribonucleotide triphosphate pyrophosphatase from Methanococ- cus jannaschii that shows a

Nicholas E. Burgis; Jason J. Brucker; Richard P. Cunningham

2003-01-01

144

Instability of repeated DNAs during transformation in Escherichia coli  

Microsoft Academic Search

Escherichia coli has provided an important model system for understanding the molecular basis for genetic instabilities associated with repeated DNA. Changes in triplet repeat length during growth following transformation in E. coli have been used as a measure of repeat instability. However, very little is known about the molecular and biological changes that may occur on transformation. Since only a

Vera I. Hashem; Elzbieta A. Klysik; William A. Rosche; Richard R. Sinden

2002-01-01

145

Transformation of Escherichia coli by a specific DNA restriction fragment  

Microsoft Academic Search

Specific transformation of a rifampicin sensitive strain of Escherichia coli to rifampicin resistance has been performed by a single, defined DNA restriction fragment carrying the genetic information for the ß subunit of E. coli RNA polymerase. In this transformation the transforming genetic character has been substituted for the corresponding recipient gene locus by recombination. The value of the described transformation

Silvia M. Schweitzer; Hans Matzura

1977-01-01

146

CNF producing Escherichia coli isolated from cattle in Northern Ireland  

Microsoft Academic Search

Tissue culture assays were used to investigate the incidence of cytotoxic necrotising factors (CNFs) 1 and 2 in Escherichia coli strains from cattle. E. coli cultures were obtained from faeces collected from 223 cases of diarrhoea and from 113 healthy animals. In addition, strains cultured from 62 cases of mastitis, 66 cases of septicaemia and 68 cases of abortion were

A. L. Burns; H. J. Ball; D. A. Finlay

1996-01-01

147

Escherichia coli Responses to a Single DNA Adduct  

Microsoft Academic Search

To study the mechanisms by which Escherichia coli modulates the genotoxic effects of DNA damage, a novel system has been developed which permits quantitative measurements of various E. coli pathways involved in mutagenesis and DNA repair. Events measured include fidelity and efficiency of translesion DNA synthesis, excision repair, and recombination repair. Our strategy involves heteroduplex plasmid DNA bearing a single

GAGAN A. PANDYA; IN-YOUNG YANG; ARTHUR P. GROLLMAN; MASAAKI MORIYA

2000-01-01

148

Gene transfer between Escherichia coli and Enterobacter aerogenes  

Microsoft Academic Search

Transfer of chromosomal genes between Escherichia coli K12 and Enterobacter aerogenes was carried out by P1-mediated transduction as well as by transformation of genes cloned in vitro on plasmid vectors. The efficient expression of E. coli genes in E. aerogenes probably reflects the existance of a poor restriction system in the latter, and suggests that this strain might be useful

Shulamit Michaeli; Eliora Z. Ron

1983-01-01

149

Transport of multiple Escherichia coli strains in saturated porous media  

Microsoft Academic Search

The deviation of bacteria transport and deposition patterns on grains in porous media from theory has resulted in the inability to accurately predict transport distances in aquifers, with consequences of polluting drinking water sources (springs, boreholes and wells). Due to the importance of Escherichia coli (E. coli) as an indicator of faecal contamination of drinking water supplies, this thesis research

G. Lutterodt

2012-01-01

150

Phenotypic and genotypic characterization of human and nonhuman escherichia coli  

Microsoft Academic Search

Estuarine waters receive fecal pollution from a variety of sources, including humans and wildlife. Escherichia coli is one of several fecal coliform bacteria that inhabit the intestines of many warm-blooded animals that sometime contaminate water. Its presence does not specifically implicate human fecal input, therefore it is necessary to differentiate contamination sources to accurately assess health risks. E. coli were

Salina Parveen; Nancy C Hodge; Robert E Stall; Samuel R Farrah; Mark L Tamplin

2001-01-01

151

Chicken Ovalbumin is Synthesized and Secreted by Escherichia coli  

Microsoft Academic Search

By recombinant DNA methods, the chicken ovalbumin structural gene has been fused to Escherichia coli lac transcriptional and translational control regions. When a plasmid containing the hybrid gene was introduced into E. coli, a protein identified as ovalbumin by immunoreactivity and sodium dodecyl sulfate\\/polyacrylamide gel electrophoresis was synthesized. The chicken ovalbumin made in bacteria was full length (43,000 daltons) and

Thomas H. Fraser; Barbara J. Bruce

1978-01-01

152

Genetic engineering of ethanol production in Escherichia coli  

Microsoft Academic Search

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

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

1987-01-01

153

Unusual "Flesh-Eating" Strain of Escherichia coli?  

PubMed Central

We report an exceptional case of life-threatening Escherichia coli-induced necrotizing fasciitis. A combined host-pathogen genetic analysis explained the phenotype: the host displayed a susceptibility to intravascular coagulation, and the strain was capable of producing a necrotic toxin (cytotoxic necrotizing factor 1), showing how E. coli can be a dermonecrotic pathogen.

Grimaldi, David; Bonacorsi, Stephane; Roussel, Helene; Zuber, Benjamin; Poupet, Helene; Chiche, Jean-Daniel; Poyart, Claire; Mira, Jean-Paul

2010-01-01

154

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

PubMed Central

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

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

1970-01-01

155

Shiga toxin-producing Escherichia coli  

PubMed Central

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

Etcheverria, Analia Ines; Padola, Nora Lia

2013-01-01

156

Enteroaggregative Escherichia coli: an emerging enteric pathogen.  

PubMed

Enteroaggregative Escherichia coli (EAEC) represents an emerging pathogen that causes enteric and food-borne infectious diseases. Subgroups in many populations throughout the world are susceptible to EAEC infection. EAEC pathogenesis involves adherence to the intestinal mucosa; increased production and deposition of a mucus biofilm; and mucosal toxicity due to inflammation and cytokine release. Due to the heterogeneity of EAEC strains and differing host immune responses, not all EAEC infections are symptomatic. Recent data suggest that individuals with a homozygous genotype -251 AA single nucleotide polymorphism (SNP), in the IL-8 promoter region, are more susceptible to EAEC diarrhea. The HEp-2 cell adherent assay allows identification of EAEC's characteristic aggregative or "stacked brick" adherence pattern. Antimicrobial treatment of individuals who develop EAEC diarrhea should be individually based. Ciprofloxacin and rifaximin, compared to placebo, have been shown to significantly shorten the course of diarrhea in patients who developed EAEC infection. The objective of this review is to increase awareness of this important emerging pathogen and to discuss the epidemiology, pathogenesis, and host-pathogen factors associated with EAEC infection. PMID:15046233

Huang, David B; Okhuysen, Pablo C; Jiang, Zhi-Dong; DuPont, Herbert L

2004-02-01

157

Conformational studies of Escherichia coli pyruvate oxidase.  

PubMed

Pyruvate oxidase (pyruvate:oxygen oxidoreductase (phosphorylating), EC 1.2.3.3) is a peripheral membrane enzyme from Escherichia coli which utilizes the cofactors thiamin pyrophosphate (TPP) and flavin-adenine dinucleotide (FAD) to catalyze the decarboxylation of pyruvate to acetic acid and carbon dioxide. The specific activity of the oxidase is enhanced 25-fold when assayed in the presence of certain lipids and detergents. Previous studies have demonstrated that the affinity of pyruvate oxidase for phospholipids and detergents is substantially increased when the flavin is reduced. In this paper, several techniques are utilized to probe both the nature of the active site and the conformational changes in the protein which are concomitant with flavin reduction and with the binding of lipids to the enzyme. Analysis of the circular dichroism spectrum in the far ultraviolet region indicates that neither the binding of lipid activators to the oxidase nor reduction of the enzyme-bound flavin by pyruvate has a significant effect on the average secondary structure of the enzyme. High-resolution electron microscopy demonstrates that at low enzyme concentrations, i.e., assay conditions, incubation of the reduced flavoprotein in the presence of an amphiphilic activator does not alter the quaternary structure of pyruvate oxidase. The results indicate that the conformational changes in the protein due either to reduction of the flavin or to the binding of lipid activators are localized. PMID:6751398

O'Brien, T A; Shelton, E; Mather, M; Gennis, R B

1982-08-10

158

Mating aggregates in Escherichia coli conjugation.  

PubMed Central

Mating mixtures of Escherichia coli cells were shown to contain mating aggregates of two to 20 cells each rather than only mating pairs of two cells each. The mating aggregate size distribution shows two broad peaks, at two to four cells and at eight to 13 cells. The quantitative mating aggregate size distribution and the proportion of male cells in mating aggregates are dependent on the input ratio of male to female cells. At an input ratio of one to one, the average mating aggregate contains equal proportions of male and female cells and most of the cells involved in mating are in large aggregates of seven or more cells each. The deoxyribonucleic acid (DNA) transfer efficiency per mating aggregate cell was constant regardless of average aggregate size or of the ratio of male to female cells in the aggregate. Under optimal conditions essentially every male cell or every female cell in a mating aggregate can be involved in DNA transfer. A comparison of light microscopy, sucrose gradient centrifugation, and analysis with a modified Coulter counter indicated that the number of cells in mating aggregates is best equantitated using a modified Coulter counter. Images

Achtman, M

1975-01-01

159

Growth rate regulation in Escherichia coli  

PubMed Central

Growth rate regulation in bacteria has been an important issue in bacterial physiology for the past 50 years. This review, using Escherichia coli as a paradigm, summarizes the mechanisms for the regulation of rRNA synthesis in the context of systems biology, particularly, in the context of genome-wide competition for limited RNA polymerase (RNAP) in the cell under different growth conditions including nutrient starvation. The specific location of the seven rrn operons in the chromosome and the unique properties of the rrn promoters contribute to growth rate regulation. The length of the rrn transcripts, coupled with gene dosage effects, influence the distribution of RNAP on the chromosome in response to growth rate. Regulation of rRNA synthesis depends on multiple factors that affect the structure of the nucleoid and the allocation of RNAP for global gene expression. The magic spot ppGpp, which acts with DksA synergistically, is a key effector in both the growth rate regulation and the stringent response induced by nutrient starvation, mainly because the ppGpp level changes in response to environmental cues. It regulates rRNA synthesis via a cascade of events including both transcription initiation and elongation, and can be explained by an RNAP redistribution (allocation) model.

Jin, Ding Jun; Cagliero, Cedric; Zhou, Yan Ning

2012-01-01

160

Isolation of the Escherichia coli nucleoid.  

PubMed

Numerous protocols for the isolation of bacterial nucleoids have been described based on treatment of cells with sucrose-lysozyme-EDTA and subsequent lysis with detergents in the presence of counterions (e.g., NaCl, spermidine). Depending on the lysis conditions both envelope-free and envelope-bound nucleoids could be obtained, often in the same lysate. To investigate the mechanism(s) involved in compacting bacterial DNA in the living cell, we wished to isolate intact nucleoids in the absence of detergents and high concentrations of counterions. Here, we compare the general lysis method using detergents with a procedure involving osmotic shock of Escherichia coli spheroplasts that resulted in nucleoids free of envelope fragments. After staining the DNA with DAPI (4',6-diamidino-2-phenylindole) and cell lysis by either isolation procedure, free-floating nucleoids could be readily visualized in fluorescence microscope preparations. The detergent-salt and the osmotic-shock nucleoids appeared as relatively compact structures under the applied ionic conditions of 1 M and 10 mM, respectively. RNase treatment caused no dramatic changes in the size of either nucleoid. PMID:11278063

Cunha, S; Odijk, T; Süleymanoglu, E; Woldringh, C L

2001-02-01

161

Nucleoside diphosphate kinase from Escherichia coli.  

PubMed Central

Nucleoside diphosphate (NDP) kinase from Escherichia coli was purified to homogeneity and was crystallized. Gel filtration analysis of the purified enzyme indicated that it forms a tetramer. The enzyme was phosphorylated with [gamma-32P]ATP, and the pH stability profile of the phosphoenzyme indicated that two different amino acid residues were phosphorylated. Both a histidine residue and serine residues, including Ser-119 and Ser-121, appear to be phosphorylated. A Ser119Ala/Ser121Ala double mutant (i.e., with a Ser-to-Ala double mutation at positions 119 and 121), as well as Ser119Ala and Ser121Ala mutants, was isolated. All of these retained NDP kinase activity; also, both the Ser119Ala and Ser121Ala mutants could still be autophosphorylated. In the case of the double mutant, a slight autophosphorylation activity, which was resistant to acid treatment, was still detected, indicating that an additional minor autophosphorylation site besides His-117 exists. These results are discussed in light of the recent report of N. J. MacDonald et al. on the autophosphorylation of human NDP kinase (J. Biol. Chem. 268:25780-25789, 1993).

Almaula, N; Lu, Q; Delgado, J; Belkin, S; Inouye, M

1995-01-01

162

Biochemistry of homologous recombination in Escherichia coli.  

PubMed Central

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

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

1994-01-01

163

Mechanisms of Acid Resistance in Escherichia coli.  

PubMed

Adaptation to acid stress is an important factor in the transmission of intestinal microbes. The enterobacterium Escherichia coli uses a range of physiological, metabolic, and proton-consuming acid resistance mechanisms in order to survive acid stresses as low as pH 2.0. The physiological adaptations include membrane modifications and outer membrane porins to reduce proton influx and periplasmic and cytoplasmic chaperones to manage the effects of acid damage. The metabolic acid resistance systems couple proton efflux to energy generation via select components of the electron transport chain, including cytochrome bo oxidase, NADH dehydrogenase I, NADH dehydrogenase II, and succinate dehydrogenase. Under anaerobic conditions the formate hydrogen lyase complex catalyzes conversion of cytoplasmic protons to hydrogen gas. Finally, each major proton-consuming acid resistance system has a pyridoxal-5'-phosphate-dependent amino acid decarboxylase that catalyzes proton-dependent decarboxylation of a substrate amino acid to product and CO2, and an inner membrane antiporter that exchanges external substrate for internal product. PMID:23701194

Kanjee, Usheer; Houry, Walid A

2013-05-20

164

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

165

Mouse Model of Enteropathogenic Escherichia coli Infection  

PubMed Central

Enteropathogenic Escherichia coli (EPEC) is an important cause of diarrhea in humans. EPEC infection of cultured intestinal epithelial cells induces attaching and effacing (A/E) lesions, alters intestinal ion transport, increases paracellular permeability, and stimulates inflammation. The lack of a small-animal model has restricted in vivo studies examining EPEC-host interactions. The aim of this study was to characterize the C57BL/6J mouse as a model of EPEC infection. We have shown that EPEC can adhere to and colonize the intestinal epithelium of C57BL/6J mice. Animal weight and water intake were not altered during 10 days of EPEC infection. The proximal colon of infected mice contained semisolid stool, with stool pellets forming only in the distal colon. In contrast, the entire colon of control mice contained formed stool. Microvillous effacement and actin rearrangement, characteristic of A/E lesions, were seen in the intestine of infected mice but not control mice. Histological assessment revealed increased numbers of lamina propria neutrophils with occasional crypt abscesses, intraepithelial lymphocytes, and goblet cells in the intestine of EPEC-infected mice. Altogether, these data suggest that the C57BL/6J mouse is susceptible to infection by EPEC and will provide a suitable in vivo model for studying the consequences of EPEC infection.

Savkovic, Suzana D.; Villanueva, Jennilee; Turner, Jerrold R.; Matkowskyj, Kristina A.; Hecht, Gail

2005-01-01

166

Characterization of an Escherichia coli elaC deletion mutant  

Microsoft Academic Search

The elaC gene of Escherichia coli encodes a binuclear zinc phosphodiesterase (ZiPD). ZiPD homologs from various species act as 3? tRNA processing endoribonucleases, and although the homologous gene in Bacillus subtilis is essential for viability [EMBO J. 22 (2003) 4534], the physiological function of E. coli ZiPD has remained enigmatic. In order to investigate the function of E. coli ZiPD

Oliver Schilling; Sabrina Rüggeberg; Andreas Vogel; Nicole Rittner; Sigrid Weichert; Sabine Schmidt; Simon Doig; Thomas Franz; Vladimir Benes; Simon C. Andrews; Michael Baum; Wolfram Meyer-Klaucke

2004-01-01

167

Inactivation of Escherichia coli in orange juice using ozone  

Microsoft Academic Search

\\u000aThis research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (106?CFU mL-?1) as a challenge microorganism was treated with ozone at 75-78??g mL-?1 for different time periods (0-18?min). The efficacy of ozone for inactivation of both strains of E. coli was

S. Patil; P. Bourke; J. M. Frias; B. K. Tiwari; P. J. Cullen

2009-01-01

168

Longevity Studies of Escherichia coli on Apples from Tree  

Microsoft Academic Search

The consumption of fresh apple juice and apple cider has been linked to increasing numbers of outbreaks associated with Escherichia coli O157:H7. Apples can become contaminated with E. coli O157:H7 not only during processing but also while still on the tree. This study was undertaken to ascertain if E. coli can survive and grow on apples in an orchard environment

Sun-Young Lee; Dong-Hyun Kang

169

Functional Homology of Chemotaxis Genes Escherichia coli and Salmonella typhimurium  

Microsoft Academic Search

Generally nonchemotactic mutants of Escherichia coli and Salmonella typhi- murium were analyzed by interspecies complementation tests to determine the functional correspondence between the che genes of these two organisms. The E. coli che region was introduced into Salnonella recipients by means of a series of F-prime elements. Wild-type che genes of E. coli F'420 complemented all che mutants of Sabnonella

Anthony L. Defranco; JOHN S. PARKINSON; D. E. KOSHLAND

1979-01-01

170

Inhibition of Escherichia coli-Induced Meningitis by Carboxyfullerence  

Microsoft Academic Search

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-1b production by staining

NINA TSAO; PUTHUPARAMPIL P. KANAKAMMA; TIEN-YAU LUH; CHEN-KUNG CHOU

1999-01-01

171

Escherichia coli : on-farm contamination of animals  

Microsoft Academic Search

Summary Escherichia coli is one of the main inhabitants of the intestinal tract of most mammalian species, including humans, and birds. Shiga toxin-producing E. coli (STEC), also called verotoxinogenic E. coli, usually do not cause disease in animals but may cause watery diarrhoea, haemorrhagic colitis, and\\/or haemolytic uraemic syndrome in humans. Zoonotic STEC include the O157:H7 strains and, with increasing

J. M. Fairbrother; É. Nadeau

2006-01-01

172

Recombinant Production of Native Proteins from Escherichia coli  

Microsoft Academic Search

\\u000a The production of large quantities of proteins became possible with the advent of recombinant DNA technology, and the subsequent\\u000a expression of recombinant proteins in Escherichia coli (E. coli) (Itakura, 1977). Recombinant proteins are produced in E. coli cytoplasm at high concentrations in a very different environment than that in which they are normally expressed. Their structure,\\u000a stability and solubility are

Tsutomu Arakawa; Tiansheng Li; Linda O. Narhi

173

The Function of OmpA in Escherichia coli  

Microsoft Academic Search

Outer membrane protein A (OmpA) is a major protein in the Escherichia coli outer membrane. In this study, the function of OmpA in E. coli stress survival was examined. An E. coli K1 ompA-deletion mutant was significantly more sensitive than that of its parent strain to sodium dodecyl sulfate (SDS), cholate, acidic environment, high osmolarity, and pooled human serum. A

Ying Wang

2002-01-01

174

Environmental Controls on the Fate of Escherichia coli in Soil  

Microsoft Academic Search

An improved understanding of factors that influence the survival and\\/or growth of Escherichia coli (E. coli) in soil is essential to allow the formation of land management practices to control the spread of the pathogenic strains\\u000a of the bacteria, whose transmission to fresh produce is a threat to food safety. Persistence of E. coli in soils held at different water

M. Habteselassie; M. Bischoff; E. Blume; B. Applegate; B. Reuhs; S. Brouder; R. F. Turco

2008-01-01

175

Antimicrobial resistance of Escherichia coli and therapeutic implications.  

PubMed

Widespread antibiotic resistance has been recognized in Escherichia coli isolates from human, animal and environmental sources. Although prevalence rates for resistant E. coli strains are significantly distinct for various populations and environments, the impact of resistance to antimicrobial drugs is ubiquitous. This article provides information about the epidemiology, mechanisms and molecular principles of resistance, shows consequences for the antiinfective treatment of selected infections and describes measures to control the spread of antibiotic-resistant E. coli. PMID:16238024

von Baum, Heike; Marre, Reinhard

2005-10-01

176

Inactivation of Escherichia coli O157:H7 and Escherichia coli 8739 in apple juice by pulsed electric fields.  

PubMed

The effect of high voltage pulsed electric field (PEF) treatment on Escherichia coli O157:H7 and generic E. coli 8739 in apple juice was investigated. Fresh apple juice samples inoculated with E. coli O157:H7 and E. coli 8739 were treated by PEF with selected parameters including electric field strength, treatment time, and treatment temperature. Samples were exposed to bipolar pulses with electric field strengths of 30, 26, 22, and 18 kV/cm and total treatment times of 172, 144, 115, and 86 micros. A 5-log reduction in both cultures was determined by a standard nonselective medium spread plate laboratory procedure. Treatment temperature was kept below 35 degrees C. Results showed no difference in the sensitivities of E. coli O157:H7 and E. coli 8739 against PEF treatment. PEF is a promising technology for the inactivation of E. coli O157:H7 and E. coli 8739 in apple juice. PMID:10419274

Evrendilek, G A; Zhang, Q H; Richter, E R

1999-07-01

177

Internalization of Escherichia coli O157:H7 following biological and mechanical disruption of growing spinach plants.  

PubMed

The internalization and persistence of a bioluminescent Escherichia coli O157:H7 Ph1 was investigated in growing spinach plants that had been either biologically or mechanically damaged. In control (undamaged) plants cultivated in soil microcosms inoculated with E. coli O157:H7 Phl, the bacterium was recovered from surface-sterilized root tissue but not from leaves. Mechanical disruption of the seminal root and root hairs of the plants did not result in the internalization of the pathogen into the aerial leaf tissue. When imprints of the root tissue were made on plates of tryptic soy agar plus ampicillin, no colonies of E. coli O157:H7 were observed around damaged tissue. The roots of growing plants were exposed to the northern root-knot nematode, Meloidogyne hapla, in the presence of E. coli O157:H7. Although this treatment caused knot formation on the roots, it did not enhance the internalization of the bacterium into the plant vascular system. Coinoculation of intact leaves with E. coli O157:H7 and the phytopathogen Pseudomonas syringae DC3000 resulted in localized necrosis, but the persistence of the human pathogen was not affected. The mechanical disruption of roots does not result in the internalization of E. coli O157:H7 into the aerial tissue of spinach, and there does not appear to be any effect of P. syringae in terms of enhancing the persistence of E. coli O157:H7 in spinach leaves. PMID:16355819

Hora, Rajneesh; Warriner, Keith; Shelp, Barry J; Griffiths, Mansel W

2005-12-01

178

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

179

Novel mechanism of Escherichia coli porin regulation.  

PubMed

A novel mechanism of Escherichia coli porin regulation was discovered from multicopy suppressors that permitted growth of cells expressing a mutant OmpC protein in the absence of DegP. Analyses of two suppressors showed that both substantially lowered OmpC expression. Suppression activities were confined to a short DNA sequence, which we designated ipeX for inhibition of porin expression, and to DNA containing a 3'-truncated ompR gene. The major effect of ipeX on ompC expression was exerted posttranscriptionally, whereas the truncated OmpR protein reduced ompC transcription. ipeX was localized within an untranslated region of 247 base pairs between the stop codon of nmpC-a remnant porin gene from the cryptic phage qsr' (DLP12) genome-and its predicted Rho-independent transcriptional terminator. Interestingly, another prophage, PA-2, which encodes a porin similar to NmpC, known as Lc, has sequences downstream from lc identical to that of ipeX. PA-2 lysogenization leads to Lc expression and OmpC inhibition. Our data show that the synthesis of the lc transcript, whose 3' end contains the corresponding ipeX sequence, inhibits OmpC expression. Overexpression of ipeX RNA inhibited both OmpC and OmpF expression but not that of OmpA. ompC-phoA chimeric gene constructs revealed a 248-bp untranslated region of ompC required for ipeX-mediated inhibition. However, no sequence complementarity was found between ipeX and this region of ompC, indicating that inhibition may not involve simple base pairing between the two RNA molecules. The effect of ipeX on ompC, but not on ompF, was independent of the RNA chaperone Hfq. PMID:16385048

Castillo-Keller, Maria; Vuong, Phu; Misra, Rajeev

2006-01-01

180

Tobramycin uptake in Escherichia coli membrane vesicles.  

PubMed Central

The uptake of tobramycin was measured in Escherichia coli membrane vesicles prepared in KMES [K(+)-2-(N-morpholino)ethanesulfonic acid] buffer at pH 6.6. Uptake occurred in vesicles energized with ascorbic acid and phenazine methosulfate, in which the electrical potential (delta psi) was -120 mV, but not in vesicles energized with D-lactate (delta psi = -95 mV). The addition of nigericin to vesicles energized with D-lactate did not induce tobramycin uptake despite an increase in delta psi to -110 mV. However, when delta psi was increased or decreased by the addition of nigericin or valinomycin, respectively, uptake in vesicles energized with ascorbic acid and phenazine methosulfate was stimulated or inhibited, respectively, confirming studies with whole cells showing that uptake of aminoglycosides is gated by delta psi rather than by proton motive force (delta microH+) or delta pH. N-ethylmaleimide prevented uptake, suggesting that the aminoglycoside transporter is a cytoplasmic membrane protein with accessible sulfhydryl groups. The observation that uptake is gated in vesicles as well as in whole cells suggested that diffusion occurs through a voltage-gated channel. In vesicles preloaded with tobramycin, no efflux occurred after the addition of the protonophore carbonyl cyanide m-chlorophenylhydrazone. In susceptible cells, aminoglycosides themselves decreased the magnitude of delta psi. We propose a mechanism of aminoglycoside-induced killing in which aminoglycosides themselves close the voltage-gated channel by decreasing the magnitude of delta psi. Channel closure causes aminoglycosides accumulated prior to the fall in delta psi to be trapped, which in turn causes irreversible uptake and subsequent bactericidal effects.

Leviton, I M; Fraimow, H S; Carrasco, N; Dougherty, T J; Miller, M H

1995-01-01

181

The Ascorbate Transporter of Escherichia coli  

PubMed Central

The sgaTBA genes of Escherichia coli encode a putative 12-transmembrane ?-helical segment (12 TMS) transporter, an enzyme IIB-like protein and an enzyme IIA-like protein of the phosphotransferase system (PTS), respectively. We show that all three proteins as well as the energy-coupling PTS proteins, enzyme I and HPr, are required for the anaerobic utilization and uptake of l-ascorbate in vivo and its phosphoenolpyruvate-dependent phosphorylation in vitro. The transporter exhibits an apparent Km for l-ascorbate of 9 ?M and is highly specific. The sgaTBA genes are regulated at the transcriptional level by the yjfQ gene product, as well as by Crp and Fnr. The yjfR gene product is essential for l-ascorbate utilization and probably encodes a cytoplasmic l-ascorbate 6-phosphate lactonase. We conclude that SgaT represents a novel prototypical enzyme IIC that functions with SgaA and SgaB to allow phosphoryl transfer from HPr(his-P) to l-ascorbate via the phosphoryl transfer pathway: PEP???enzyme?I-P???HPr-P???IIA-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{SgaA} \\\\ P \\\\ }\\, }\\end{equation*}\\end{document}???IIB-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{SgaB} \\\\ P \\\\ }\\, }\\end{equation*}\\end{document}\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{IIC} \\\\ {\\rightarrow} \\\\ }\\, }\\end{equation*}\\end{document}SgaTl-ascorbate-6-P.

Zhang, Zhongge; Aboulwafa, Mohammad; Smith, Meghan H.; Saier, Jr., Milton H.

2003-01-01

182

Differential analysis of bactericidal systems of blood serum with recombinant luminescent Escherichia coli and Bacillus subtilis strains.  

PubMed

Luminescence intensity of recombinant Escherichia coli and Bacillus subtilis strains with cloned luxCD(AB)E genes of the natural luminescent microorganism Photobacterium leiognathi was studied under the influence of 30 individual samples of human blood serum of different component composition. A relationship was found between the level of residual bioluminescence and degree of the bactericidal effect. Moreover, the inhibition of E. coli lux+ luminescence was shown to be related to activity of the complement-lysozyme system. The reaction of B. subtilis lux+ primarily depended on the presence of ?-lysin in the blood serum. These data provide an experimental substantiation of a new method of differential analysis of humoral factors of nonspecific innate immunity with recombinant luminescent bacteria. PMID:23330091

Deryabin, D G; Karimov, I F; Manukhov, I V; Tolmacheva, N A; Balabanov, V P

2012-11-01

183

Proteins on Escherichia coli andAgrobacterium tumefaciens Translation Systems  

Microsoft Academic Search

Theeffects of30type1andof2 (ricin andvolkensin) type2ribosome-inactivating proteins (RIPs) on Escherichia coli andAgrobacterium tumefaciens cell-free translation systems were compared withtheeffects on a rabbit reticulocyte translation system. Thedepurinating activity ofRIPson E.coli ribosomes was also evaluated. Onlysixtype1RIPsinhibited endogenous mRNA-directed translational activity ofE.coli lysates, withsubmicromolar 50% inhibitory concentrations. FourRIPshadsimilar activities on poly(U)-directed phenylalanine polymerization byE.coli ribosomes, andthree RIPsinhibited poly(U)-directed polyphenylala- ninesynthesis byA.tumefaciens ribosomes, withsubmicromolar 50%1inhibitory

TOMAS GIRBES; MIGUEL FERRERAS; F. JAVIER ARIAS; M. ANGELES ROJO; ROSARIO IGLESIAS; CARLOS ALEGRE; FIORENZO STIRPE

184

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

185

Serological cross-reactions between Escherichia coli O157 and other species of the genus Escherichia.  

PubMed

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 polyclonal antisera and in the slide agglutination assay by using latex reagents. Only four isolates (17%) of E. hermannii exhibited serological cross-reactivity. PMID:1583138

Rice, E W; Sowers, E G; Johnson, C H; Dunnigan, M E; Strockbine, N A; Edberg, S C

1992-05-01

186

Transcriptome of Uropathogenic Escherichia coli during Urinary Tract Infection  

Microsoft Academic Search

A uropathogenic Escherichia coli strain CFT073-specific DNA microarray that includes each open reading frame was used to analyze the transcriptome of CFT073 bacteria isolated directly from the urine of infected CBA\\/J mice. The in vivo expression profiles were compared to that of E. coli CFT073 grown statically to exponential phase in rich medium, revealing the strategies this pathogen uses in

Jennifer A. Snyder; Brian J. Haugen; Eric L. Buckles; C. Virginia Lockatell; David E. Johnson; Michael S. Donnenberg; Rodney A. Welch; Harry L. T. Mobley

2004-01-01

187

Escherichia coli Cytochrome c Nitrite Reductase NrfA  

Microsoft Academic Search

The periplasmic cytochrome c nitrite reductase (Nrf) system of Escherichia coli utilizes nitrite as a respiratory electron acceptor by reducing it to ammonium. Nitric oxide (NO) is a proposed intermediate in this six-electron reduction and NrfA can use exogenous NO as a substrate. This chapter describes the method used to assay Nrf-catalyzed NO reduction in whole cells of E. coli

Paul C. Mills; Susie R. Poock; Myles R. Cheesman; Jeffrey A. Cole; Jay C. D. Hinton; Andrew M. Hemmings; k Stephen Spiro; Jessica Van Wonderen; David J. Richardson

188

Mechanisms of Acid Resistance in Enterohemorrhagic Escherichia coli  

Microsoft Academic Search

Enterohemorrhagic strains ofEscherichia colimust pass through the acidic gastric barrier to cause gastro- intestinal disease. Taking into account the apparent low infectious dose of enterohemorrhagic E. coli ,1 1 O157:H7 strains and 4 commensal strains of E. coli were tested for their abilities to survive extreme acid exposures (pH 3). Three previously characterized acid resistance systems were tested. These included

GEORGE N. BENNETT; ANDJOHN W. FOSTER

1996-01-01

189

Genes and proteins of Escherichia coli K-12.  

PubMed

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

Riley, M

1998-01-01

190

Large surface blebs on Escherichia coli heated to inactivating temperatures.  

PubMed

Large surface blebs were observed with phase-contrast optics on Escherichia coli B/r and B(s-1) heated to temperatures at which colony-forming ability was lost. Characterization of such blebs was consistent with the view that they were formed by a physical process and were bounded by the outer membrane of the cell. A hypothesis for thermal inactivation of E. coli is presented that places membrane damage near the primary lethal event. PMID:4196258

Scheie, P; Ehrenspeck, S

1973-05-01

191

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

192

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

193

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

194

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

195

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

196

Naturalized Escherichia coli from New Zealand wetland and stream environments.  

PubMed

This research investigates the presence of a naturalized clade of Escherichia coli in wetland and stream biofilms. Escherichia coli is used as a faecal indicator in water quality monitoring programmes worldwide, with the assumption that this bacterium is exclusively a commensal of the vertebrate gut. However, recent findings indicate growth and multiplication of E. coli in water and soils. This study seeks to clarify the relationships between environmental and commensal E. coli strains retrieved from New Zealand streams by evaluating fundamental genetic differences using the multilocus sequence typing (MLST) method. Environmental and commensal strains showed a high diversity of MLST profiles. Genetic analyses of linkage disequilibrium, index of association and rates of synonymous and nonsynonymous substitutions were used to investigate sequence variability and nature of change. Phylogenetic trees based on the concatenated sequences of the seven MLST housekeeping genes displayed distinct clustering of environmental strains. Comparison of the New Zealand sequences with worldwide E. coli strains retrieved from the Shigatox MLST database online did not allow the identification of a clear environmental genotype. However, some New Zealand aquatic E. coli isolates showed close relationships with strains from human and bovine origins, suggesting that environmental isolates were originally derived from subpopulations of commensal E. coli from these sources. PMID:22974403

Perchec-Merien, Anne-Marie; Lewis, Gillian D

2012-10-08

197

Homolactate Fermentation by Metabolically Engineered Escherichia coli Strains  

Microsoft Academic Search

We report the homofermentative production of lactate in Escherichia coli strains containing mutations in the aceEF, pfl, poxB, and pps genes, which encode the pyruvate dehydrogenase complex, pyruvate formate lyase, pyruvate oxidase, and phosphoenolpyruvate synthase, respectively. The process uses a defined medium and two distinct fermentation phases: aerobic growth to an optical density of about 30, followed by nongrowth, anaerobic

Y. Zhu; M. A. Eiteman; K. DeWitt; E. Altman

2007-01-01

198

What's for Dinner?: Entner-Doudoroff Metabolism in Escherichia coli  

Microsoft Academic Search

The Entner-Doudoroff (ED) pathway was first discovered in 1952 in Pseudomonas saccharophila (21) and several years later was shown to be present in Escherichia coli (23). Although generally considered to be restricted to gram-negative bacteria, the ED pathway is present in all three phylogenetic domains, including the most deeply rooted Archaea (18). The ubiquity of the ED pathway suggests that

N. PEEKHAUS; T. CONWAY

1998-01-01

199

Conformational pathways in the gating of Escherichia coli mechanosensitive channel  

Microsoft Academic Search

The pathway of the gating conformational transition of Escherichia coli mechanosensitive channel was simulated, using the recently modeled open and closed structures, by targeted molecular dynamics method. The transition can be roughly viewed as a four-stage process. The initial motion under a lower tension load is predominantly elastic deformation. The opening of the inner hydrophobic pore on a higher tension

Yifei Kong; Yufeng Shen; Tiffany E. Warth; Jianpeng Ma

2002-01-01

200

Effective Immunomodulatory Treatment of Escherichia coli Experimental Sepsis with Thalidomide  

Microsoft Academic Search

Thalidomide, an agent which inhibits biosynthesis of tumor necrosis factor alpha (TNF-) and which is used to treat a variety of chronic inflammatory conditions, was investigated as therapy for experimental sepsis. Sepsis was induced by intraperitoneal injection of 107 CFU of Escherichia coli per kg of body weight to 80 Wistar rats divided into four groups. Group A consisted of

Evangelos J. Giamarellos-Bourboulis; Helen Poulaki; Nikolaos Kostomitsopoulos; Ismene Dontas; Despina Perrea; Panayotis E. Karayannacos; Helen Giamarellou

2003-01-01

201

Evolution of Escherichia coli During Growth in a Constant Environment  

Microsoft Academic Search

Populations of Escherichia coli, initiated with a single clone and maintained for long periods in glucose-limited continuous culture, developed extensive polymorphisms. In one population, examined after 765 generations, two majority and two minority types were identified. Stable mixed populations were reestablished from the isolated strains. Factors involved in the development of this polymorphism included differences in the maximum specific growth

Robert B. Helling; Christopher N. Vargas; Julian Adams

1987-01-01

202

Escherichia coli and other Enterobacteriaceae: Food poisoning and health effects  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

203

Escherichia coli swim on the right-hand side  

Microsoft Academic Search

The motion of peritrichously flagellated bacteria close to surfaces is relevant to understanding the early stages of biofilm formation and of pathogenic infection. This motion differs from the random-walk trajectories of cells in free solution. Individual Escherichia coli cells swim in clockwise, circular trajectories near planar glass surfaces. On a semi-solid agar substrate, cells differentiate into an elongated, hyperflagellated phenotype

Willow R. Diluzio; Linda Turner; Michael Mayer; Piotr Garstecki; Douglas B. Weibel; Howard C. Berg; George M. Whitesides

2005-01-01

204

Enterotoxigenic Escherichia coli Infection in Captive Black-footed Ferrets  

Microsoft Academic Search

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 ni- gripes) 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

Gregory A. Bradley; Kathy Orr; Carlos Reggiardo; Robert D. Glock

205

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

206

Electrooptical analysis of the Escherichia coli–phage interaction  

Microsoft Academic Search

This article describes electrooptical (EO) characterization of biospecific binding between the bacterium Escherichia coli XL-1 and the phage M13K07. The electrooptical analyzer (ELUS EO), which has been developed at the State Research Center for Applied Microbiology, Obolensk, Russia, was used as the basic instrument for EO measurements. The operating principle of the analyzer is based on the polarizability of microorganisms,

Victor D Bunin; Oleg V Ignatov; Olga I Guliy; Irina S Zaitseva; Daniel O’Neil; Dmitri Ivnitski

2004-01-01

207

Covert Operations of Uropathogenic Escherichia coli within the Urinary Tract  

Microsoft Academic Search

Entry into host cells is required for many bacterial patho- gens to effectively disseminate within a host, avoid immune detection and cause disease. In recent years, many ostensibly extracellular bacteria have been shown to act as opportunistic intracellular pathogens. Among these are strains of uropathogenic Escherichia coli (UPEC), the primary causative agents of urinary tract infections (UTIs). UPEC are able

Jean M. Bower; Danelle S. Eto; Matthew A. Mulvey

2005-01-01

208

Prediction of rho-independent transcriptional terminators in Escherichia coli  

Microsoft Academic Search

A new algorithm called RNAMotif containing RNA structure and sequence constraints and a thermo- dynamic scoring system was used to search for intrinsic rho-independent terminators in the Escherichia coli K-12 genome. We identified all 135 reported terminators and 940 putative terminator sequences beginning no more than 60 nt away from the 3'-end of the annotated transcription units (TU). Putative and

Elena A. Lesnik; Rangarajan Sampath; Harold B. Levene; Timothy J. Henderson; John A. McNeil; David J. Ecker

2001-01-01

209

Marine macroalgae as a source for osmoprotection for Escherichia coli  

Microsoft Academic Search

At elevated osmolarity of the mineral medium M63, marine macroalgae constitute important osmoprotectants and nutrients sources for Escherichia coli. Growth of bacterial population (16 strains) was improved by supplementing M63 salts medium with either aqueous or ethanolic algal extracts obtained from Ascophyllum nodosum, Fucus serratus, Enteromorpha ramulosa, Ulva lactuca, and Palmaria palmata. In their presence, growth was still observed even

M. Ghoul; J. Minet; T. Bernard; E. Dupray; M. Cormier

1995-01-01

210

Quorum sensing in Escherichia coli and Salmonella typhimurium  

Microsoft Academic Search

Escherichia coli and Salmonella typhimurium strains grown in Luria-Bertani medium containing glucose secrete a small soluble heat labile organic molecule that is involved in intercellular communication. The factor is not produced when the strains are grown in Luria-Bertani me- dium in the absence of glucose. Maximal secretion of the substance occurs in midexponential phase, and the extracel- lular activity is

MICHAEL G. SURETTE; BONNIE L. BASSLER

1998-01-01

211

A DNA structural atlas for Escherichia coli1  

Microsoft Academic Search

We have performed a computational analysis of DNA structural features in 18 fully sequenced prokaryotic genomes using models for DNA curva- ture, DNA flexibility, and DNA stability. The structural values that are computed for the Escherichia coli chromosome are significantly different from (and generally more extreme than) that expected from the nucleo- tide composition. To aid this analysis, we have

Anders Gorm Pedersen; Lars Juhl Jensen; Søren Brunak; Hans-Henrik Stærfeldt; David W. Ussery

2000-01-01

212

Physical map of the Escherichia coli K12 genome  

Microsoft Academic Search

A physical map of a genome is the structure of its DNA. Construction of such a map is a first step in the complete characterization of that DNA. The restriction endonuclease Not I cuts the genome of Escherichia coli K12 into 22 DNA fragments ranging from 20 kilobases (20,000 base pairs) to 1000 kilobases. These can be separated by pulsed

C. L. Smith; J. G. Econome; A. Schutt; S. Klco; C. R. Cantor

1987-01-01

213

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

214

The effects of daunomycin and ethidium bromide on Escherichia coli  

Microsoft Academic Search

The effects of two DNA-intercalating agents daunomycin (DMC) and ethidium bromide (EBR) on transcription, translation and replication in Escherichia coli have been studied. The data are consistent with the notion that low concentrations of these drugs primarily inhibit transcription and replication to equal extents and that translation is halted indirectly as a result of the decay of the messenger RNA

T. Tønnesen; J. D. Friesen

1973-01-01

215

Metabolic Switching in the Sugar Phosphotransferase System of Escherichia coli  

Microsoft Academic Search

Bacteria grown in a mixture of multiple sugars will first metabolize a preferred sugar until it is nearly depleted, only then turning to other carbon sources in the medium. This sharp switching of metabolic preference is characteristic of systems that optimize fitness. Here we consider the mechanism by which switching can occur in the Escherichia coli phosphotransferase system (PTS), which

Mukund Thattai; Boris I. Shraiman

2003-01-01

216

Visualizing multiple constrictions in spheroidal Escherichia coli cells  

Microsoft Academic Search

Abstract — An Escherichia coli cell grows,by elongation and divides in a perpendicular plane. Alternating planes of successive divisions in three dimensions can only be ascertained when multiple constrictions exist simultaneously in large, spheroidal cells (with extended constriction process), if the division signals are enhanced. Large, spheroidal cells are obtained by a brief mecillinam treatment, and more frequent divisions are

A. Zaritsky; Geel van A. B. M; I. Fishov; E. Pas; M. Einav; C. L. Woldringh

1999-01-01

217

Escherichia coli Cellulitis in Children With Idiopathic Nephrotic Syndrome  

Microsoft Academic Search

Although Streptococcus pneumoniae is traditionally considered the preponderant bacterial pathogen in children with nephrotic syndrome, recent data suggest an increase of infections with encapsulated gram-negative organisms. We report two children with idiopathic nephrotic syndrome in relapse who developed spontaneous Escherichia coli cellulitis. The organism was recovered from the cellulitis tissue aspirate of one, and from the blood of the other.

Basim I. Asmar; Bassam N. Bashour; Larry E. Fleischmann

1987-01-01

218

Expression of Thiobacillus ferrooxidans origin of replication in Escherichia coli  

SciTech Connect

A cryptic plasmid from an autotrophically grown arsenic-resistant strain of Thiobacillus ferrooxidans was isolated and cloned into pBR325. The origin of replication of pBR325 was deleted, and the recombinant plasmid was shown to replicate in Escherichia coli, using an origin of replication located on the Thiobacillus plasmid.

Rawlings, D.E.; Pretorius, I.; Woods, D.R.

1984-05-01

219

Serotyping and biotyping of 160 Escherichia coli strains: comparative study.  

PubMed Central

One hundred and sixty Escherichia coli strains were serotyped and biotyped. Serotyping revealed 68 different types, with 25 strains not typable. Biotyping was possible in all strains but revealed 55 different types. One biotype could be subdivided into 35 different serotypes, indicating that for this biotype the series of biochemical and fermentation reactions could be extended for further differentiation.

Van Der Waaij, D; Speltie, T M; Guinee, P A; Agterberg, C

1975-01-01

220

Exploitation of host cells by enteropathogenic Escherichia coli  

Microsoft Academic Search

Microbial pathogens have evolved many ingenious ways to infect their hosts and cause disease, including the subversion and exploitation of target host cells. One such subversive microbe is enteropathogenic Escherichia coli (EPEC). A major cause of infantile diarrhea in developing countries, EPEC poses a significant health threat to children worldwide. Central to EPEC-mediated disease is its colonization of the intestinal

B. A. Vallance; B. B. Finlay

2000-01-01

221

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

222

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

223

The Evolutionary History of Shigella and Enteroinvasive Escherichia coli Revised  

Microsoft Academic Search

In Shigella and enteroinvasive Escherichia coli (EIEC), the etiologic agents of shigellosis in humans, the determinants responsible for entry of bacteria into and dissemination within epithelial cells are encoded by a virulence plasmid. To understand the evolution of the association between the virulence plasmid and the chromosome, we performed a phylogenetic analysis using the sequences of four chromosomal genes (

Patricia Escobar-Páramo; Catherine Giudicelli; Claude Parsot; Erick Denamur

2003-01-01

224

Strategies for efficient production of heterologous proteins in Escherichia coli  

Microsoft Academic Search

In recent years, the number of recombinant proteins used for therapeutic applications has increased dramatically. Production of these proteins has a remarkable demand in the market. Escherichia coli offers a means for the rapid and economical production of recombinant proteins. These advantages, coupled with a wealth of biochemical and genetic knowledge, have enabled the production of such economically therapeutic proteins

S. Jana; J. K. Deb

2005-01-01

225

Modeling hexavalent chromium reduction in Escherichia coli 33456  

Microsoft Academic Search

A model based on the analysis of the mechanism of enzymatic reaction was developed to characterize the rate and extent of microbial reduction of hexavalent chromium in Escherichia coli 33456. A finite reduction capacity (R[sub c]) was proposed and incorporated into the enzymatic model to regulate the toxicity effect on cells due to the oxidizing power of Cr(6). The parameter

Hai Shen; Yi-Tin Wang

1994-01-01

226

DNA degradation in minicells of Escherichia coli K-12  

Microsoft Academic Search

The properties of minicell producing mutants of Escherichia coli deficient in gentic recombination were examined. Experiments were designed to test recombinant formation in conjugal crosses, survival following UV-irradiation in cells, and the state of DNA metabolism in minicells. The REC- phenotypes are unaffected by min+\\/- genotypes in whole cells. In contrast to minicells produced by rec+ parental cells, minicells from

George G. Khachatourians; M. C. Paterson; Ronald J. Sheehy; B. Van Dorp; T. E. Worthy

1975-01-01

227

Growth-rate dependent RNA polyadenylation in Escherichia coli  

Microsoft Academic Search

RNA polyadenylation occurs not only in eukaryotes but also in bacteria. In prokaryotes, polyadenylated RNA molecules are usually degraded more efficiently than non-modified transcripts. Here we demonstrate that two transcripts, which were shown previously to be substrates for poly(A) polymerase I (PAP I), Escherichia coli lpp messenger RNA and bacteriophage ? oop RNA, are polyadenylated more efficiently in slowly growing

Jacek Jasiecki

2003-01-01

228

Global Gene Expression Responses to Cadmium Toxicity in Escherichia coli  

PubMed Central

Genome-wide analysis of temporal gene expression profiles in Escherichia coli following exposure to cadmium revealed a shift to anaerobic metabolism and induction of several stress response systems. Disruption in the transcription of genes encoding ribosomal proteins and zinc-binding proteins may partially explain the molecular mechanisms of cadmium toxicity.

Wang, Anyou; Crowley, David E.

2005-01-01

229

MICROARRAY BASED COMPARISON OF TWO ESCHERICHIA COLI 0157 LINEAGES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previous research has identified the potential for the existence of two separate lineages of Escherichia coli O157:H7. Clinical isolates tended to cluster with only one of these two lineages. To determine if there are common genes differentially expressed between the two lineages, we chose to utiliz...

230

Antibiotic resistance in Escherichia coli from Nigerian students, 1986 1998.  

PubMed Central

We tested 758 fecal Escherichia coli isolates, recovered from Nigerian students in 1986, 1988, 1990, 1994, and 1998, for susceptibility to seven antimicrobial drugs. The prevalences of strains resistant to tetracycline, ampicillin, chloramphenicol, and streptomycin were 9% to 35% in 1986 and 56% to 100% in 1998. These findings demonstrate that resistance gene reservoirs are increasing in healthy persons.

Okeke, I. N.; Fayinka, S. T.; Lamikanra, A.

2000-01-01

231

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

232

Methods for Detecting Enterohaemorrhagic Escherichia Coli in Food  

Microsoft Academic Search

Enterohaemorrhagic Escherichia coli (EHEC) serogroup determines worldwide foodborne illnesses and remains one of the major concerns for the population and for the food industry. These strains, indeed, determine gastrointestinal disease varying from diarrhoea to haemorrhagic colitis, haemolytic uraemic syndrome, and thrombotic thrombocytopaenic purpura. Classic detection methods are based on specific enrichment, often coupled with immunomagnetic separation system, specific media, and

Rossana Sidari; Andrea Caridi

2011-01-01

233

Uropathogenic Escherichia coli Flagella Aid in Efficient Urinary Tract Colonization  

Microsoft Academic Search

In the murine model of urinary tract infections (UTI), cystitis by uropathogenic Escherichia coli (UPEC) occurs through an intimate relationship with the bladder superficial umbrella cell entailing cycles of adher- ence, invasion, intracellular bacterial community (IBC) formation, and dispersal (fluxing) from the intracel- lular environment. IBC dispersal is a key step that results in the spread of bacteria over the

Kelly J. Wright; Patrick C. Seed; Scott J. Hultgren

2005-01-01

234

Escherichia coli induces apoptosis and proliferation of mammary cells  

Microsoft Academic Search

Mammary cell apoptosis and proliferation were assessed after injection of Escherichia coli into the left mammary quarters of six cows. Bacteriological analysis of foremilk samples revealed coliform infection in the injected quarters of four cows. Milk somatic cell counts increased in these quarters and peaked at 24 h after bacterial injection. Body temperature also increased, peaking at 12 h postinjection.

E Long; A V Capuco; D L Wood; T Sonstegard; G Tomita; M J Paape; X Zhao

2001-01-01

235

Effects of Hyperoxia on Sulfhydryl Concentration of 'Escherichia coli'.  

National Technical Information Service (NTIS)

The concentration of reduced sulfhydryl (SH) in cell-free extracts of Escherichia coli grown with air as the gas phase was 26.8 plus or minus 1.2 mnoles SH/mg soluble protein. Exposure of bacteria to 1 ata of oxygen where growth continued but at a reduced...

J. L. Stees O. R. Brown

1972-01-01

236

Pressure-Sensitive Ion Channel in Escherichia coli  

Microsoft Academic Search

We have used the patch-clamp electrical recording technique on giant spheroplasts of Escherichia coli and have discovered pressure-activated ion channels. The channels have the following properties: (i) activation by slight positive or negative pressure; (ii) voltage dependence; (iii) large conductance; (iv) selectivity for anions over cations; (v) dependence of activity on the species of permeant ions. We believe that these

Boris Martinac; Matthew Buechner; Anne H. Delcour; Julius Adler; Ching Kung

1987-01-01

237

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

238

Sex and virulence in Escherichia coli: an evolutionary perspective  

PubMed Central

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.

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

2006-01-01

239

Removal of Escherichia coli in wastewater by activated sludge.  

PubMed Central

Removal of bacteria from wastewater treated with activated sludge was studied by the use of a streptomycin-resistant Escherichia coli strain. The removal appeared to be a biphasic process. A rapid sorption of bacteria to the sludge flocs took place in the first hour after seeding mixed liquor with E. coli. Thereafter, slower elimination of E. coli was observed. The latter process was due to predation on E. coli by ciliated protozoa. This was shown by: (i) appearance of fluorescent food vacuoles of ciliates when fluorescent E. coli cells were added to mixed liquor; (ii) inhibition of predation either in the presence of cycloheximide or under anaerobic conditions; and (iii) absence of predation in bulking and washed sludge. Images

van der Drift, C; van Seggelen, E; Stumm, C; Hol, W; Tuinte, J

1977-01-01

240

A Critical Examination of Escherichia coli Esterase Activity*  

PubMed Central

The ability of Escherichia coli to grow on a series of acetylated and glycosylated compounds has been investigated. It is surmised that E. coli maintains low levels of nonspecific esterase activity. This observation may have ramifications for previous reports that relied on nonspecific esterases from E. coli to genetically encode nonnatural amino acids. It had been reported that nonspecific esterases from E. coli deacetylate tri-acetyl O-linked glycosylated serine and threonine in vivo. The glycosylated amino acids were reported to have been genetically encoded into proteins in response to the amber stop codon. However, it is our contention that such amino acids are not utilized in this manner within E. coli. The current results report in vitro analysis of the original enzyme and an in vivo analysis of a glycosylated amino acid. It is concluded that the amber suppression method with nonnatural amino acids may require a caveat for use in certain instances.

Antonczak, Alicja K.; Simova, Zuzana; Tippmann, Eric M.

2009-01-01

241

A critical examination of Escherichia coli esterase activity.  

PubMed

The ability of Escherichia coli to grow on a series of acetylated and glycosylated compounds has been investigated. It is surmised that E. coli maintains low levels of nonspecific esterase activity. This observation may have ramifications for previous reports that relied on nonspecific esterases from E. coli to genetically encode nonnatural amino acids. It had been reported that nonspecific esterases from E. coli deacetylate tri-acetyl O-linked glycosylated serine and threonine in vivo. The glycosylated amino acids were reported to have been genetically encoded into proteins in response to the amber stop codon. However, it is our contention that such amino acids are not utilized in this manner within E. coli. The current results report in vitro analysis of the original enzyme and an in vivo analysis of a glycosylated amino acid. It is concluded that the amber suppression method with nonnatural amino acids may require a caveat for use in certain instances. PMID:19666472

Antonczak, Alicja K; Simova, Zuzana; Tippmann, Eric M

2009-08-07

242

Injury by heavy metals in Escherichia coli  

SciTech Connect

The aim of the present study on the effects of sublethal concentrations of metals on the growth and recovery of E. coli, is to throw light on some of the aspects of the viability and recovery of E. coli as well as changes in its cell enzymatic activity when exposed to sublethal concentrations of heavy metals. Total dehydrogenase was used since it is a measure of bacterial activity closely related to energetic metabolic systems and ..beta..-galactosidase as a typical inducible enzyme in E. coli. E. coli was chosen as the test organism, both on account of its importance in public health (sanitary indicators) and for the information available (biochemical and genetic properties) on it.

Cenci, G.; Morozzi, G.; Caldini, G.

1985-02-01

243

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

PubMed

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

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

2013-01-30

244

Evolution of the iss gene in Escherichia coli.  

PubMed

The increased serum survival gene iss has long been recognized for its role in extraintestinal pathogenic Escherichia coli (ExPEC) virulence. iss has been identified as a distinguishing trait of avian ExPEC but not of human ExPEC. This gene has been localized to large virulence plasmids and shares strong similarities with the bor gene from bacteriophage lambda. Here, we demonstrate that three alleles of iss occur among E. coli isolates that appear to have evolved from a common lambda bor precursor. In addition to the occurrence of iss on the ColV/BM virulence plasmids, at least two iss alleles occur within the E. coli chromosome. One of these alleles (designated type 3) was found to occur in the genomes of all currently sequenced ExPEC strains on a similar prophage element that also harbors the Sit iron and manganese transport system. When the prevalence of the three iss types was examined among 487 E. coli isolates, the iss type 3 gene was found to occur at a high frequency among ExPEC isolates, irrespective of the host source. The plasmid-borne iss allele (designated type 1) was highly prevalent among avian pathogenic E. coli and neonatal meningitis-associated E. coli isolates but not among uropathogenic E. coli isolates. This study demonstrates the evolution of iss in E. coli and provides an additional tool for discriminating among E. coli pathotypes through the differentiation of the three iss allele types and bor. PMID:18281426

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

2008-02-15

245

INHIBITION OF OXIDATIVE PHOSPHORYLATION IN ESCHERICHIA COLI BY DIHYDROSTREPTOMYCIN  

PubMed Central

Bragg, P. D. (University of British Columbia, Vancouver, B.C., Canada), and W. J. Polglase. Inhibition of oxidative phosphorylation in Escherichia coli by dihydrostreptomycin. J. Bacteriol. 86:1236–1240. 1963.—Dihydrostreptomycin inhibited the oxidation of succinate in extracts of antibiotic-sensitive Escherichia coli. The inhibitable reaction required both the particulate and the supernatant fractions from sonic extracts which had been centrifuged at 100,000 × g. Dihydrostreptomycin was found to inhibit phosphorylation coupled with the oxidation of reduced nicotinamide adenine dinucleotide (NADH). The inhibition of oxidative phosphorylation by dihydrostreptomycin appeared to precede the effect of the antibiotic on oxidation. The streptomycin antagonist, 2-heptyl-4-hydroxyquinoline N-oxide, inhibited the oxidation of succinate and of NADH, but showed little effect on oxidative phosphorylation. Oxidative phosphorylation was not affected by dihydrostreptomycin in strains of E. coli which were antibiotic-resistant or -dependent.

Bragg, P. D.; Polglase, W. J.

1963-01-01

246

Kinetics of bacteriophage lambda deoxyribonucleic acid infection of Escherichia coli.  

PubMed

Barnhart, Benjamin J. (Los Alamos Scientific Laboratory, University of California, Los Alamos, N.M.). Kinetics of bacteriophage lambda deoxyribonucleic acid infection of Escherichia coli. J. Bacteriol. 90:1617-1623. 1965.-The kinetics of Escherichia coli K-12 infection by phage lambda deoxyribonucleic acid (DNA) were determined. An initial lag of 55 to 80 sec was found to be the time required for infecting DNA to become deoxyribonuclease-insensitive at 33 C. When cell-DNA interactions were stopped by washing away unbound DNA, the already bound DNA continued to infect the cell at rates described by linear kinetics with no apparent lag. Whereas the lag period was relatively insensitive to DNA and cell concentrations, both the lag and the subsequent linear portions of the rate curves were temperature-sensitive. Cell and DNA dose-response curves prescribed hyperbolic functions. Similarities between lambda DNA infection of E. coli and bacterial transformation systems are discussed. PMID:5322721

Barnhart, B J

1965-12-01

247

Adhesive threads of extraintestinal pathogenic Escherichia coli  

PubMed Central

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

2009-01-01

248

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

249

Fate of Escherichia coli during Ensiling of Wheat and Corn†  

PubMed Central

A recombinant Escherichia coli strain carrying a plasmid with an antibiotic resistance marker and expressing the green fluorescent protein was inoculated at a concentration of 3.8 × 108 CFU/g into direct-cut wheat (348 g of dry matter kg?1), wilted wheat (450 g of dry matter kg?1), and corn (375 g of dry matter kg?1). The forages were ensiled in mini-silos. The treatments included control (no E. coli added), application of tagged E. coli, and delayed sealing of the inoculated wheat. Three silos per treatment were sampled on predetermined dates, and the numbers of E. coli were determined on Chromocult TBX medium with or without kanamycin. Colonies presumptively identified as E. coli were also tested for fluorescence activity. Addition of E. coli at the time of ensiling resulted in a more rapid decrease in the pH but had almost no effect on the chemical composition of the final silages or their aerobic stability. E. coli disappeared from the silages when the pH decreased below 5.0. It persisted longer in silages of wilted wheat, in which the pH declined more slowly. Control silages of all crops also contained bacteria, presumptively identified as E. coli, that were resistant to the antibiotic, which suggests that some epiphytic strains are naturally resistant to antibiotics.

Chen, Y.; Sela, S.; Gamburg, M.; Pinto, R.; Weinberg, Z. G.

2005-01-01

250

Engineered synthetic pathway for isopropanol production in Escherichia coli.  

PubMed

A synthetic pathway was engineered in Escherichia coli to produce isopropanol by expressing various combinations of genes from Clostridium acetobutylicum ATCC 824, E. coli K-12 MG1655, Clostridium beijerinckii NRRL B593, and Thermoanaerobacter brockii HTD4. The strain with the combination of C. acetobutylicum thl (acetyl-coenzyme A [CoA] acetyltransferase), E. coli atoAD (acetoacetyl-CoA transferase), C. acetobutylicum adc (acetoacetate decarboxylase), and C. beijerinckii adh (secondary alcohol dehydrogenase) achieved the highest titer. This strain produced 81.6 mM isopropanol in shake flasks with a yield of 43.5% (mol/mol) in the production phase. To our knowledge, this work is the first to produce isopropanol in E. coli, and the titer exceeded that from the native producers. PMID:17933911

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

2007-10-12

251

Escherichia coli resistance to quinolones at a comprehensive cancer center.  

PubMed

As part of Meropenem Yearly Susceptibility Test Information Collection/USA Surveillance Programme, we monitored the occurrence of quinolone resistance in Escherichia coli over a 10-year period. A total of 271 E. coli isolates from our institution were tested over a 10-year period. Screening for quinolone resistance (qnr) gene was performed. A decline in susceptibility of E. coli isolates to quinolones and aminoglycosides was noted over the 10-year span (P < 0.0001), which was significantly reduced compared with the average susceptibility of all sites. Introduction of quinolone prophylaxis has led to a significant decline in susceptibility of E. coli to all quinolones. The organisms remain susceptible to carbapenems, cefepime, and piperacillin/tazobactam. Periodic surveillance allows for detection of resistance patterns and adjustment of empiric antibiotic choice in patients at high risk for infection. PMID:20471765

Mihu, Coralia N; Rhomberg, Paul R; Jones, Ronald N; Coyle, Elizabeth; Prince, Randall A; Rolston, Kenneth V

2010-05-15

252

Engineered Synthetic Pathway for Isopropanol Production in Escherichia coli? †  

PubMed Central

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

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

2007-01-01

253

Biosynthesis of bioactive O-methylated flavonoids in Escherichia coli.  

PubMed

Two bioactive O-methylflavonoids, sakuranetin (7-O-methylnaringenin) and ponciretin (7-O-methylnaringenin), were synthesized in Escherichia coli. Sakuranetin inhibits germination of Magnaporthe grisea, and ponciretin is a potential inhibitor of Helicobacter pylori. To achieve this, we reconstructed the naringenin biosynthesis pathway in E. coli. First, the shikimic acid pathway, which leads to the biosynthesis of tyrosine, was engineered in E. coli to increase the amount of available tyrosine. Second, several genes for the biosynthesis of ponciretin and sakuranetin such as tyrosine ammonia lyase (TAL), 4-coumaroyl CoA ligase (4CL), chalcone synthase (CHS), and O-methyltransferase (OMT) were overexpressed. In order to increase the supply the Coenzyme A (CoA), one gene (icdA, isocitrate dehydrogenase) was deleted. Using these strategies, we synthesized ponciretin and sakuranetin from glucose in E. coli at the concentration of 42.5 mg/L and 40.1 mg/L, respectively. PMID:23771780

Kim, Min-Ji; Kim, Bong-Gyu; Ahn, Joong-Hoon

2013-06-15

254

Proton-linked D-xylose transport in Escherichia coli.  

PubMed Central

The addition of xylose to energy-depleted cells of Escherichia coli elicited an alkaline pH change which failed to appear in the presence of uncoupling agents. Accumulation of [14C]xylose by energy-replete cells was also inhibited by uncoupling agents, but not by fluoride or arsenate. Subcellular vesicles of E. coli accumulated [14C]xylose provided that ascorbate plus phenazine methosulfate were present for respiration, and this accumulation was inhibited by uncoupling agents or valinomycin. Therefore, the transport of xylose into E. coli appears to be energized by a proton-motive force, rather than by a phosphotransferase or directly energized mechanism. Its specificity for xylose as inducer and substrate and the genetic location of a xylose-H+ transport-negative mutation near mtl showed that the xylose-H+ system is distinct from other proton-linked sugar transport systems of E. coli.

Lam, V M; Daruwalla, K R; Henderson, P J; Jones-Mortimer, M C

1980-01-01

255

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

256

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

257

Purification of penicillin-binding protein 2 of Escherichia coli.  

PubMed Central

Penicillin-binding protein 2 (PBP-2) of Escherichia coli K-12 was purified by covalent affinity chromatography using 6-aminopenicillanic acid covalently coupled to carboxymethyl-Sepharose (6-APA-CM-Sepharose). Purification of PBP-2 was accomplished by prebinding the methoxy cephalosporin, cefoxitin, to the Triton X-100-solubilized PBPs of E. coli and then incubating the PBPs with 6-APA-CM-Sepharose. Cefoxitin readily binds to all the E. coli PBPs except PBP-2 and, thus, in the presence of cefoxitin, only PBP-2 could bind to the 6-APA-CM-Sepharose. The purification of a mixture of all of the PBPs of E. coli by affinity chromatography is also described. Images

Curtis, S J; Strominger, J L

1981-01-01

258

Quantitative determination of Escherichia coli in water using CHROMagar ® E. coli  

Microsoft Academic Search

A new medium, CHROMagar®E. coli (CAEC), containing a combination of X-glucuronide and methyl-glucuronide for the detection of ?-glucuronidase activity of Escherichia coli has been evaluated by the membrane filtration (MF) technique n fresh water samples. The CAEC agar was compared with conventional media, mFC agar and mLSB, for the enumeration of faecal coliforms. The variance analysis showed that CAEC was

Jose L. Alonso; Inmaculada Amoros; Steven Chong; Hemda Garelick

1996-01-01

259

Rapid detection of pathogens using antibody-coated microbeads with bioluminescence in microfluidic chips  

Microsoft Academic Search

Detection of pathogens was demonstrated in a polydimethylsiloxane (PDMS)\\/glass microfluidic chip with which microbead-based\\u000a immunoseparation platform and the bioluminescence technology were integrated. Escherichia coli (E. coli) O157:H7 was used as the model bacteria. The microchamber in microfluidic chip was filled with glass beads coated with antibodies\\u000a which could capture specific organism, and the capture efficiency of the chip for the

Xiao Guan; Hui-jing Zhang; Yin-nan Bi; Li Zhang; Dun-ling Hao

2010-01-01

260

Sensing of plant hydrolysate-related phenolics with an aaeXAB::luxCDABE bioreporter strain of Escherichia coli.  

PubMed

A bioluminescent Escherichia coli bioreporter strain to detect hydrolysate related phenolics was developed by cloning the aaeXAB promoter from E. coli upstream of the luxCDABE genes. E. coli str. DH5? carrying this plasmid (pDMA3) was responsive to sub-inhibitory concentrations of plant hydrolysate-related phenolics, such as ferulic and vanillic acids, responding to these compounds at concentrations as low as 9.8 and 4.9 mg/L, respectively. Experiments with a mixture of the compounds showed similar responses as with single compound tests, with a minimum detectable concentration of 19.5mg/L. Finally, tests using rice straw hydrolysates were conducted, with E. coli str. DH5?/pDMA3 showing a maximum induction of 33-fold and a minimum detectable phenolic concentration of 9.3mg/L, based upon Folin-Ciocalteu's reagent. These results demonstrate that this bioreporter maintains its sensitivity even with hydrolysate samples and that it can be potentially applied within biofuel industries to detect phenolics present within plant hydrolysates. PMID:23138066

Monnappa, Ajay Kalanjana; Lee, Siseon; Mitchell, Robert J

2012-09-29

261

Vero response to a cytotoxin of Escherichia coli.  

PubMed Central

A cytotoxin was found in culture filtrates of a number of Escherichia coli strains that differed from the known heat-stable and heat-labile enterotoxins of E. coli. It was cytotoxic for Vero but not for Y-1 or CHO cells, and its effect on Vero was distinctly different from that of heat-labile enterotoxin. It was labile to heat and antigenically different from heat-labile enterotoxin, and membrane filtration indicated a molecular weight of 10,000 to 30,000. Images

Konowalchuk, J; Speirs, J I; Stavric, S

1977-01-01

262

Genes and proteins of Escherichia coli (GenProtEc).  

PubMed

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

Riley, M; Space, D B

1996-01-01

263

Genetic Transformation in Escherichia coli K12  

Microsoft Academic Search

An auxotrophic strain of E. coli K12 treated with CaCl2 was transformed for several markers at a frequency of up to 10-6 per recipient cell by a DNA preparation isolated from a prototrophic strain. The transforming activity of the DNA preparation was eliminated by treatment with DNase, heat, or sonication, whereas RNase or Pronase treatment had little effect. Two closely

Sharon D. Cosloy; Michio Oishi

1973-01-01

264

Molecular prophage typing of avian pathogenic Escherichia coli.  

PubMed

Escherichia coli prophages confer virulence and resistance to physico-chemical, nutritional, and antibiotic stresses on their hosts, and they enhance the evolution of E. coli. Thus, studies on profiles of E. coli prophages are valuable to understand the population structure and evolution of E. coli pathogenicity. Large terminase genes participate in phage genome packaging and are one of the cornerstones for the identification of prophages. Thus, we designed primers to detect 16 types of large terminase genes and analyzed the genomes of 48 E. coli and Shigella reference strains for the prophage markers. We also investigated the distribution of the 16 prophage markers among 92 avian pathogenic E. coli (APEC) strains. APEC strains were classified into 61 prophage types (PPTs). Each strain was different from the reference strains as measured by the PPTs and from the frequency of each prophage marker. Investigation of the distribution of prophage-related serum resistance (bor), toxin (stx1 and cdtI), and T3SS effector (lom, espK, sopE, nleB, and ospG) genes revealed the presence of bor (44.1%), lom (95.5%) and cdtI (9.1%) in APEC strains with related prophages. Therefore, the molecular prophage typing method may be useful to understand population structure and evolution of E. coli pathogenicity, and further studies on the mobility of the prophages and the roles of virulence genes in APEC pathogenicity may be valuable. PMID:23102989

Kwon, Hyuk-Joon; Seong, Won-Jin; Kim, Jae-Hong

2012-10-16

265

Escherichia coli induces apoptosis and proliferation of mammary cells.  

PubMed

Mammary cell apoptosis and proliferation were assessed after injection of Escherichia coli into the left mammary quarters of six cows. Bacteriological analysis of foremilk samples revealed coliform infection in the injected quarters of four cows. Milk somatic cell counts increased in these quarters and peaked at 24 h after bacterial injection. Body temperature also increased, peaking at 12 h postinjection. The number of apoptotic cells was significantly higher in the mastitic tissue than in the uninfected control. Expression of Bax and interleukin-1beta converting enzyme increased in the mastitic tissue at 24 h and 72 h postinfection, whereas Bcl-2 expression decreased at 24 h but did not differ significantly from the control at 72 h postinfection. Induction of matrix metalloproteinase-9, stromelysin-1 and urokinase-type plasminogen activator was also observed in the mastitic tissue. Moreover, cell proliferation increased in the infected tissue. These results demonstrate that Escherichia coli-induced mastitis promotes apoptosis and cell proliferation. PMID:11526434

Long, E; Capuco, A V; Wood, D L; Sonstegard, T; Tomita, G; Paape, M J; Zhao, X

2001-08-01

266

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

267

Succinate dehydrogenase and fumarate reductase from Escherichia coli  

Microsoft Academic Search

Succinate-ubiquinone oxidoreductase (SQR) as part of the trichloroacetic acid cycle and menaquinol-fumarate oxidoreductase (QFR) used for anaerobic respiration by Escherichia coli are structurally and functionally related membrane-bound enzyme complexes. Each enzyme complex is composed of four distinct subunits. The recent solution of the X-ray structure of QFR has provided new insights into the function of these enzymes. Both enzyme complexes

Gary Cecchini; Imke Schröder; Robert P Gunsalus; Elena Maklashina

2002-01-01

268

Reversion of a streptomycin-dependent strain of Escherichia coli  

Microsoft Academic Search

A streptomycin dependent, spectinomycin resistant mutant ofEscherichia coli was used to select spontaneous phenotypic revertants to non-dependence on streptomycin. The ribosomes from one such revertant, which is inhibited by both streptomycin and spectinomycin, were analyzedin vitro. The altered protein responsible for the suppression of the streptomycin dependent phenotype was identified; this protein is 30S-10. The genetic locus for this mutation

E. A. BridGE; C. G. Kuriland

1970-01-01

269

Single protein production (SPP) system in Escherichia coli  

Microsoft Academic Search

Here, we provide a detailed protocol for the single protein production (SPP) system, which is designed to produce only a single protein of interest in living Escherichia coli cells. Induction of MazF, an mRNA interferase that cleaves RNA at ACA nucleotide sequences, results in complete cell growth arrest. However, if mRNA encoding a protein of interest is engineered to be

Motoo Suzuki; Lili Mao; Masayori Inouye

2007-01-01

270

Characterization of Mutations Contributing to Sulfathiazole Resistance in Escherichia coli  

Microsoft Academic Search

A sulfathiazole-resistant dihydropteroate synthase (DHPS) present in two different laboratory strains of Escherichia coli repeatedly selected for sulfathiazole resistance was mapped to folP by P1 transduction. The folP mutation in each of the strains was shown to be identical by nucleotide sequence analysis. A single C3T transition resulted in a Pro3Ser substitution at amino acid position 64. Replacement of the

GAYATRI VEDANTAM; GORDON G. GUAY; NATASHA E. AUSTRIA; STELLA Z. DOKTOR; BRIAN P. NICHOLS

1998-01-01

271

Carbon nutrition of Escherichia coli in the mouse intestine  

Microsoft Academic Search

Whole-genome expression profiling revealed Escherichia coli MG1655 genes induced by growth on mucus, conditions designed to mimic nutrient availability in the mammalian intestine. Most were nutritional genes corresponding to catabolic pathways for nutrients found in mucus. We knocked out several pathways and tested the relative fitness of the mutants for colonization of the mouse intestine in competition with their wild-type

Dong-Eun Chang; Darren J. Smalley; Don L. Tucker; Mary P. Leatham; Wendy E. Norris; Sarah J. Stevenson; April B. Anderson; Joe E. Grissom; David C. Laux; Paul S. Cohen; Tyrrell Conway

2004-01-01

272

Purification of DNA for bacterial productivity estimates. [Escherichia coli  

SciTech Connect

(methyl-{sup 3}H)thymidine-labeled DNA from natural populations of aquatic bacteria was completely separated from RNA and protein by hydroxylapatite chromatography. The procedure was validated by monitoring increases in Escherichia coli cell count, A{sup 550}, DNA concentration, and thymidine incorporation into DNA isolated by the proposed technique. The procedure can be used in the field and does not rely on the use of acid-base hydrolysis or volatile organic solvents.

Burnison, B.K.; Nuttley, D.J. (National Water Research Institute, Burlington, Ontario (Canada))

1990-02-01

273

Plastic encapsulation of stabilized Escherichia coli and Pseudomonas putida.  

PubMed

Escherichia coli and Pseudomonas putida dried in hydroxyectoine or trehalose are shown to be highly resistant to the organic solvents chloroform and acetone, and consequently, they can be encapsulated in a viable form in solid plastic materials. Bacteria are recovered by rehydration after physical disruption of the plastic. P. putida incorporated into a plastic coating of maize seeds was shown to colonize roots efficiently after germination. PMID:15128579

Manzanera, M; Vilchez, S; Tunnacliffe, A

2004-05-01

274

Recombinant expression of bioactive peptide lunasin in Escherichia coli  

Microsoft Academic Search

Lunasin, a cancer-preventive peptide, was isolated from soybean, barley, and wheat. Previous studies showed that this 43-amino\\u000a acid peptide has the ability to suppress chemical carcinogen-induced transformation in mammalian cells and skin carcinogenesis\\u000a in mice. In this study, we attempted to use the Escherichia coli T7 expression system for expression of lunasin. The lunasin gene was synthesized by overlapping extension

Chin-Feng Liu; Tzu-Ming Pan

2010-01-01

275

Effect of Zinc in Enteropathogenic Escherichia coli Infection  

Microsoft Academic Search

Enteropathogenic Escherichia coli (EPEC) infection triggers the release of ATP from host intestinal cells, and the ATP is broken down to ADP, AMP, and adenosine in the lumen of the intestine. Ecto-5-nucleotidase (CD73) is the main enzyme responsible for the conversion of 5-AMP to adenosine, which triggers fluid secretion from host intestinal cells and also has growth-promoting effects on EPEC

John K. Crane; Tonniele M. Naeher; Irina Shulgina; Chengru Zhu; Edgar C. Boedeker

2007-01-01

276

Enteroaggregative Escherichia coli diarrhea in travelers: response to rifaximin therapy  

Microsoft Academic Search

Background & Aims: We have recently shown that enteroaggregative Escherichia coli (EAEC) strains commonly cause travelers’ diarrhea. The study was designed to determine whether U.S. travelers with EAEC diarrhea responded to rifaximin therapy. Methods: In a multicenter placebo-controlled clinical trial of travelers’ diarrhea without non-EAEC pathogens we evaluated 2 doses of rifaximin. EAEC was sought in stool samples in enrolled

Rosa M Infante; Charles D Ericsson; Zhi-Dong Jiang; Shi Ke; Robert Steffen; Lise Riopel; David A Sack

2004-01-01

277

Enteroaggregative Escherichia coli Diarrhea in Travelers: Response to Rifaximin Therapy  

Microsoft Academic Search

Background & Aims: We have recently shown that en- teroaggregative Escherichia coli (EAEC) strains com- monly cause travelers'diarrhea. The study was designed to determine whether U.S. travelers with EAEC diarrhea responded to rifaximin therapy. Methods: In a multi- center placebo-controlled clinical trial of travelers'diar- rhea without non-EAEC pathogens we evaluated 2 doses of rifaximin. EAEC was sought in stool samples

ROSA M. INFANTE; CHARLES D. ERICSSON; ZHI-DONG JIANG; SHI KE; ROBERT STEFFEN; LISE RIOPEL; DAVID A. SACK; HERBERT L. DUPONT

2004-01-01

278

Lanthanide Accumulation inthePeriplasmic Spaceof Escherichia coli B  

Microsoft Academic Search

Treatment ofgrowing Escherichia coli Bwithlanthanide ions(lanthanum(III), terbium(III), andeuropi- um(III)) andsubsequent aldehyde-Os04 fixation caused areas ofhighcontrast toappear within theperiplasm (the space between inner andouter membrane ofthecell envelope). X-raymicroanalysis ofultrathin sections ofEpon-embedded oracrylic resin-embedded cells revealed thepresence ofthelanthanide andofphosphorus intheareas, whosecontrast greatly exceeded that ofother stained structures. Comparatively small amounts of thelanthanide werealsopresent intheouter membraneandinthecytoplasm. Thedistribution ofthe periplasmic areas ofhighcontrast wasfoundtoberandomandnotclustered atareas

M. E. BAYER; M. H. BAYER

1991-01-01

279

DNA plasmid production in different host strains of Escherichia coli  

Microsoft Academic Search

We compared plasmid DNA production in 13 strains of Escherichia coli in shake flasks using media containing glucose or glycerol. DNA yield from either carbon source showed small correlation\\u000a with maximum growth rate. Three strains, SCS1-L, BL21 and MC4100, were selected for a controlled exponential fed-batch process\\u000a at a growth rate of 0.14 h?1 to an optical density of about 70,

Adam Singer; Mark A. Eiteman; Elliot Altman

2009-01-01

280

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

281

Crystal Structure of DNA Photolyase from Escherichia Coli  

Microsoft Academic Search

Photolyase repairs ultraviolet (UV) damage to DNA by splitting the cyclobutane ring of the major UV photoproduct, the cis,syn-cyclobutane pyrimidine dimer (PyrPyr). The reaction is initiated by blue light and proceeds through long-range energy transfer, single electron transfer, and enzyme catalysis by a radical mechanism. The three-dimensional crystallographic structure of DNA photolyase from Escherichia coli is presented and the atomic

Hee-Won Park; Sang-Tae Kim; Aziz Sancar; Johann Deisenhofer

1995-01-01

282

Mutations affecting activity and transport of haemolysin in Escherichia coli  

Microsoft Academic Search

Temperature-sensitive mutants that exhibit an altered haemolytic phenotype were isolated from Escherichia coli harbouring the plasmid pHly152. Complementation with recombinant plasmids carrying one of the four hly genes (C, A, B or D) allowed localization of the hlyts mutations. A ts mutation in hlyC leads to a pro?leu exchange in amino acid position 53 of HlyC. Two ts mutations in

Albrecht Ludwig; Monika Vogel; Werner Goebel

1987-01-01

283

The nus mutations affect transcription termination in Escherichia coli  

Microsoft Academic Search

The nusA1 and nusB5 mutations result in a partial suppression of polarity and thus transcription termination in Escherichia coli. As these mutations block the transcription antitermination activity of bacteriophage lambdaN gene product, they paradoxically seem to enhance transcription termination atphage termination sites. The rho mutation HDF026 displays almost identical properties. These observations suggest that the nusA and nusB gene products

Douglas F. Ward; Max E. Gottesman

1981-01-01

284

Antibacterial efficacy of silver nanoparticles against Escherichia coli  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

285

Photoreactivation of enterohemorrhagic Escherichia coli following UV disinfection  

Microsoft Academic Search

The objective of this study is to determine the susceptibility of enterohemorrhagic Escherichia coli O157:H7 and O26 to UV radiation at 254nm and photoreactivation. The conclusions obtained in this study can be summarized as follows. (1) The dose of UV light required for 90 and 99% inactivation of EHEC O157:H7 was 1.5 and 3.0mWscm?2, respectively. (2) The dose of UV

K. Tosa; T. Hirata

1999-01-01

286

Conditional-lethal deoxyribonucleic acid ligase mutant of Escherichia coli.  

PubMed Central

A new Escherichia coli deoxyribonucleic acid (DNA) ligase mutant has been identified among a collection of temperature-sensitive DNA replication mutants isolated recently (Sevastopoulos, Wehr, and Glaser, Proc. Natl. Acad. Sci. U.S.A. 74:3485-3489, 1977). At the nonpermissive temperature DNA synthesis in the mutant stops rapidly, the DNA is degraded to acid-soluble material, and cell death ensures. This suggests that the mutant may be among the most ligase-deficient strains yet characterized.

Dermody, J J; Robinson, G T; Sternglanz, R

1979-01-01

287

Genetic Analysis of the Maltose A Region in Escherichia coli  

PubMed Central

The genetic map of the maltose A locus of Escherichia coli contains at least three closely linked genes, malT, malP, and malQ. The order of these genes is established by deletion mapping. MalP and malQ, the presumed structural genes for maltodextrin phosphorylase and amylomaltase, belong to the same operon. MalT may be a regulator gene involved in the positive control of this operon.

Hatfield, Dolph; Hofnung, Maurice; Schwartz, Maxime

1969-01-01

288

Environmental factors affecting indole production in Escherichia coli  

Microsoft Academic Search

A variety of both Gram-positive and Gram-negative bacteria produce large quantities of indole as an intercellular signal in microbial communities. Biosynthesis of indole is well-studied, and while carbon sources and amino acids are important environmental cues for indole production in Escherichia coli, other environmental factors affecting indole production for this strain are less clear. This study demonstrates that the environmental

Thi Hiep Han; Jin-Hyung Lee; Moo Hwan Cho; Thomas K. Wood; Jintae Lee

2011-01-01

289

Escherichia coli and Salmonella 2000: the View From Here  

PubMed Central

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.

Schaechter, Moselio

2001-01-01

290

Peptidoglycan structure in differently shaped Escherichia coli cells  

Microsoft Academic Search

Using the technique of continuous cultivation Escherichia coli W7 (dapA, lysA) has been grown in medium in which diaminopimelic acid (dap) was the limiting substrate for growth. It may be assumed that cells of this strain growing under these conditions will have adapted their peptidoglycan metabolism in such a way that the utilization ofdap is minimized but sufficient to ensure

F. Driehuis; J. T. M. Wouters

1985-01-01

291

Timing of FtsZ assembly in Escherichia coli  

Microsoft Academic Search

The timing of the appearance of the FtsZ ring at the future site of division in Escherichia coli was determined by in situ immunofluorescence microscopy for two strains grown under steady-state conditions. The strains, B\\/rA and K-12 MC4100, differ largely in the duration of the D period, the time between termination of DNA replication and cell division. In both strains

TANNEKE DEN BLAAUWEN; NIENKE BUDDELMEIJER; MIRJAM E. G. AARSMAN; COR M. HAMEETE; NANNE NANNINGA

1999-01-01

292

Enhanced Shock Wave-Assisted Transformation of Escherichia coli  

Microsoft Academic Search

The objective of the study was to demonstrate that shock wave-induced transfer of DNA into bacteria can be increased by enhancing cavitation using dual-pulse (tandem) shock waves. Escherichia coli and plasmid were transferred to test vials. Competent cells were prepared at different concentrations of CaCl2. Single pulses and tandem shock waves were compared as were three treatment temperatures: 0, 10

Achim M. Loske; Juan Campos-Guillen; Francisco Fernández; Eduardo Castaño-Tostado

2011-01-01

293

Emr, an Escherichia coli Locus for Multidrug Resistance  

Microsoft Academic Search

An Escherichia coli chromosomal DNA fragment cloned on a multicopy plasmid conferred resistance to carbonylcyanide m-chlorophenylhydrazone, nalidixic acid, and a number of other toxic compounds. The sequence of the cloned emr locus located at minute 57.5 of the chromosome revealed two open reading frames, emrA and emrB. emrB encodes a highly hydrophobic 56.2-kDa peptide, with 14 potential alpha-helices to span

Olga Lamovskaya; Kim Lewis

1992-01-01

294

Metabolic engineering of Escherichia coli for 1-butanol production  

Microsoft Academic Search

Compared to ethanol, butanol offers many advantages as a substitute for gasoline because of higher energy content and higher hydrophobicity. Typically, 1-butanol is produced by Clostridium in a mixed-product fermentation. To facilitate strain improvement for specificity and productivity, we engineered a synthetic pathway in Escherichia coli and demonstrated the production of 1-butanol from this non-native user-friendly host. Alternative genes and

Shota Atsumi; Anthony F. Cann; Michael R. Connor; Claire R. Shen; Kevin M. Smith; Mark P. Brynildsen; Katherine J. Y. Chou; Taizo Hanai; James C. Liao

2008-01-01

295

Ozone-initiated disinfection kinetics of Escherichia coli in water  

Microsoft Academic Search

The effect of ozonation on the rate of disinfection of Escherichia coli was investigated as a function of ozone concentration, ozonation duration and flow rates. Ozone was generated in situ using Corona discharge method using compressed oxygen stream and depending on the oxygen flux the ozone concentrations ranged from 0.91–4.72 mg\\/L. The rate of disinfection of all the three microbes

Favourite Zuma; Johnson Lin; Sreekanth B. Jonnalagadda

2009-01-01

296

Solar radiation induces sublethal injury in Escherichia coli in seawater.  

PubMed Central

Sublethal injury was noted in Escherichia coli after cells were exposed to solar radiation. Injury was detected by differential plate counts between complete and minimal media that were observed with sunlight-exposed cells but not with cells kept in the dark. Since addition of catalase or pyruvate to minimal medium overcame or repaired this injury, the catalase system appeared to be the site of injury.

Kapuscinski, R B; Mitchell, R

1981-01-01

297

Transcriptional Regulation of the esp Genes of Enterohemorrhagic Escherichia coli  

Microsoft Academic Search

We have determined that the genes encoding the secreted proteins EspA, EspD, and EspB of enterohemor- rhagic Escherichia coli (EHEC) are organized in a single operon. The esp operon is controlled by a promoter located 94 bp upstream from the ATG start codon of the espA gene. The promoter is activated in the early logarithmic growth phase, upon bacterial contact

FABRIZIO BELTRAMETTI; ANDREAS U. KRESSE; CARLOS A. GUZMAN

1999-01-01

298

Another gene affecting sexual expression of Escherichia coli.  

PubMed Central

We have examined the relationship between two chromosomal mutations of Escherichia coli K-12, fexA (0 min) and fexB (85 min), in regulating expression of the F sex factor. Together, fexA and fexB exert a pleiotropic effect on the expression of the F tra genes. F pilus synthesis, conjugal donor activity, and surface exclusion activity are all inhibited in the fexA fexB mutant. Either fex mutation alone is cryptic.

Lerner, T J; Zinder, N D

1982-01-01

299

Transforming activity of plasmid and chromosomal DNA in Escherichia coli  

Microsoft Academic Search

An auxotrophic strain ofEscherichia coli with therecB recC sbcB genotype was transformed by chromosomal DNA of the prototrophic strain and by plasmid DNA carrying genes for antibiotic resistance\\u000a (R1drd 19). The donor plasmid DNA obtained by cell lysis in the presence of Triton X-100 and subsequent centrifugation in a caesium\\u000a chloride-ethidium bromide gradient was shown to have a circulaf molecule

M. Šrogl; J. Hochmannová; J. Nešvera; J. Štokrová; M. Klégr

1977-01-01

300

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

301

Escherichia coli acid resistance: tales of an amateur acidophile  

Microsoft Academic Search

Gastrointestinal pathogens are faced with an extremely acidic environment. Within moments, a pathogen such as Escherichia coli O157:H7 can move from the nurturing pH 7 environment of a hamburger to the harsh pH 2 milieu of the stomach. Surprisingly, certain microorganisms that grow at neutral pH have elegantly regulated systems that enable survival during excursions into acidic environments. The best-characterized

John W. Foster

2004-01-01

302

Expression and characterization of Pichia etchellsii ?-glucosidase in Escherichia coli  

Microsoft Academic Search

The ?-glucosidase enzyme is important as the terminal enzyme involved in hydrolysis of cellobiose and short-chain cellodextrins generated during enzymatic cellulose degradation. Under controlled reaction conditions the enzyme also displays cello-oligosaccharide synthesizing ability (based on either the thermodynamic or kinetic approach). We present here the purification of the enzyme ?-glucosidase (BGL) of Pichia etchellsii from recombinant pBG55 Escherichia coli clone.

Manjula Pandey; Saroj Mishra

1997-01-01

303

Gene structure in the histidine operon of Escherichia coli  

Microsoft Academic Search

The bifunctional enzyme imidazoleglycerolphosphate dehydratase and histidinolphosphate phosphatase is encoded by the hisB gene. The fourth gene of the histidine operon, hisB, was cloned and mapped on a 2,300 base pair DNA fragment. In the present study we report the complete nucleotide sequence of the hisB gene of Escherichia coli. The gene is 1,068 nucleotides long and codes for a

Lorenzo Chiariotti; Anna Giulia Nappo; Maria Stella Carlomagno; Carmelo Bruno Bruni

1986-01-01

304

Ozone-induced damage of Escherichia coli K-12  

Microsoft Academic Search

Escherichia coli K-12 transformed with pACYC184 plasmid DNA was exposed to ozone (O3) in aqueous solution. The damage to the membrane, protein, plasmid DNA, and cell survival were investigated. Cell viability\\u000a was unaffected by short-term O3 exposure (1–5 min) but membrane permeability was compromised as indicated by protein and nucleic acid leakage and lipid oxidation.\\u000a The intracellular components, protein and

I. R. Komanapalli; B. H. S. Lau

1996-01-01

305

Relationship between Phenotypic and Genotypic Florfenicol Resistance in Escherichia coli  

Microsoft Academic Search

This study evaluated the relationship between florfenicol resistance and flo genotypes in 1,987 Escherichia coli isolates from cattle. The flo gene was detected in 164 isolates, all of which expressed resistance to florfenicol at MICs of >256 g\\/ml. The florfenicol MICs for all isolates that lacked flo were <16 g\\/ml. Florfenicol is a fluorinated analog of chloramphenicol ap- proved by

Randall S. Singer; Sheila K. Patterson; Anne E. Meier; Jessica K. Gibson; Hannah L. Lee; Carol W. Maddox

2004-01-01

306

Action of cloxacillin and Nafcillin on Escherichia coli  

Microsoft Academic Search

Résumé Divers aspects de l'action de la cloxacilline et de la nafcilline surEscherichia coli ont été étudiés. La cloxacilline s'est montrée plus efficace que la nafcilline quand il s'agissait d'arrêter la croissance et d'amener la lyse et la formation de sphéroplastes; par contre, elle s'est montrée moins efficace que plusieurs autres pénicillines (y compris l'acide 6-aminopénicillanique) à ces égards. Ces

A. D. Russell

1968-01-01

307

Febrile urinary tract infection: Escherichia coli susceptibility to oral antimicrobials  

Microsoft Academic Search

Empirical treatment is indicated for young children with febrile urinary tract infection (UTI). In this clinical setting,\\u000a oral antibiotics are as safe and effective as intravenous therapy. The aim of this study was to investigate in children with\\u000a febrile UTI whether there were longitudinal changes in the prevalence of bacteria and in the pattern of Escherichia coli susceptibility to oral

Noemia P. Goldraich; Angélica Manfroi

2002-01-01

308

Functional requirements for heat induced genome amplification in Escherichia coli  

Microsoft Academic Search

A temperature shift-up induces extra rounds of fully replicated chromosomes in Escherichia coli and leads to an increase in DNA\\/mass ratio. In the present work we characterize the requirements for this heat-induced replication (HIR) with respect to replisome components, replication restart, and recombination functions. We found that HIR requires Klenow and 5?–3? exonuclease activities from Pol I and Pol III,

Rocío González-Soltero; Alfonso Jiménez-Sánchez; Emilia Botello

2008-01-01

309

Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation.  

PubMed Central

Titanium dioxide in the anatase crystalline form was used as a photocatalyst to generate hydroxyl radicals in a flowthrough water reactor. Experiments were performed on pure cultures of Escherichia coli in dechlorinated tap water and a surface water sample to evaluate the disinfection capabilities of the reactor. In water devoid of significant amounts of inorganic-radical scavengers, rapid cell death was observed with both pure cultures and members of the indigenous flora in a natural water sample.

Ireland, J C; Klostermann, P; Rice, E W; Clark, R M

1993-01-01

310

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

311

Involvement of a plasmid in Escherichia coli envelope alterations.  

PubMed Central

A plasmid-containing wild-type Escherichia coli strain was treated with two plasmid-curing agents, sodium dodecyl sulfate and ethidium bromide. Plasmid elimination was accompanied by drastic changes in the morphology of the colonies. Analysis of the cured strain by scanning and transmission electron microscopy showed important alterations in size and morphology of the cells. Metabolic differences were also found between the wild-type and cured cells. Images

Rosas, S B; Calzolari, A; La Torre, J L; Ghittoni, N E; Vasquez, C

1983-01-01

312

Gene replacement techniques for Escherichia coli genome modification  

Microsoft Academic Search

The subject of this review covers modern experimental procedures for chromosomal gene replacement in Escherichia coli and related bacteria, which enable the specific substitution of targeted genome sequences with copies of those carrying defined\\u000a mutations. Two principal methods for gene replacement were established. The first “in–out” method is based on integration\\u000a of plasmid into bacterial chromosome and subsequent resolving of

Mahesh Madyagol; Hend Al-Alami; Zdeno Levarski; Hana Drahovská; Ján Tur?a; Stanislav Stuchlík

313

Zn(II)Induced Cooperativity of Escherichia coli Ornithine Transcarbamoylase  

Microsoft Academic Search

The steady-state reaction of ornithine transcarbamoylase (ornithine carbamoyltransferase, carbamoyl phosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) purified from the argI gene product of Escherichia coli strain K-12 exhibits Michaelis-Menten kinetics over an extended range of concentration for both L-ornithine and carbamoyl phosphate. In the presence of Zn2+, however, the saturation curve of L-ornithine becomes sigmoidal, revealing positive cooperativity for this anabolic enzyme. The

Lawrence C. Kuo; William N. Lipscomb; Evan R. Kantrowitz

1982-01-01

314

Escherichia coli iron enterobactin uptake monitored by Moessbauer spectroscopy  

Microsoft Academic Search

Iron uptake by Escherichia coli under aerobic conditions of iron deficiency is mediated by a highly stable ferric enterobactin (Fe(ent)\\/sup 3 -\\/) siderophore complex. Moessbauer spectroscopy has been used to monitor the fate of the iron as ⁵⁷Fe(ent) was taken up by the cells. Osmotic shock experiments were used to distinguish between the iron present in the periplasmic space and

B. F. Matzanke; D. J. Ecker; T. S. Yang; B. H. Huynh; G. Mueller; K. N. Raymond

1986-01-01

315

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

Microsoft Academic Search

Whole-genome sequencing has been skewed toward bacterial pathogens as a consequence of the prioritiza- tion 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.

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

2008-01-01

316

Low level of cross-resistance between triclosan and antibiotics in Escherichia coli K-12 and E. coli O55 compared to E. coli O157  

Microsoft Academic Search

Misuse of biocides has encouraged the emergence of resistance and cross-resistance in certain strains. This study investigated resistance of triclosan-adapted Escherichia coli K-12 and E. coli O55 to antimicrobial agents and compared these to E. coli O157:H7. Cross-resistance in E. coli K-12 and E. coli O55 was observed however to a lesser extent than in E. coli O157:H7. Triclosan-adapted E.

Maria Braoudaki; Anthony Craig Hilton

2004-01-01

317

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

318

Incidence of Escherichia coli in black walnut meats.  

PubMed

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

Meyer, M T; Vaughn, R H

1969-11-01

319

The production of polyhydroxyalkanoates in recombinant Escherichia coli.  

PubMed

Polyhydroxyalkanoates, the natural polyester that many microorganisms accumulate to store carbon and reducing equivalents, have been considered as a future alternative of traditional plastic due to their special properties. In Escherichia coli, a previous non-polyhydroxyalkanoates producer, pathway engineering has been developed as a very powerful approach to set up microbial production process through the introduction of direct genetic changes by recombinant DNA technology. Various metabolic pathways leading to the polyhydroxyalkanoates accumulation with desirable properties at low-cost and high-productivity have been developed. At the same time, high density fermentation technology of E. coli provides an efficient polyhydroxyalkanoates production strategy. This review focused on metabolic engineering, fermentation and downstream process aiming to polyhydroxyalkanoates production in E. coli. PMID:17097289

Li, Rui; Zhang, Hanxing; Qi, Qingsheng

2006-11-09

320

Codon reassignment in the Escherichia coli genetic code  

PubMed Central

Most organisms, from Escherichia coli to humans, use the ‘universal’ genetic code, which have been unchanged or ‘frozen’ for billions of years. It has been argued that codon reassignment causes mistranslation of genetic information, and must be lethal. In this study, we successfully reassigned the UAG triplet from a stop to a sense codon in the E. coli genome, by eliminating the UAG-recognizing release factor, an essential cellular component, from the bacterium. Only a few genetic modifications of E. coli were needed to circumvent the lethality of codon reassignment; erasing all UAG triplets from the genome was unnecessary. Thus, UAG was assigned unambiguously to a natural or non-natural amino acid, according to the specificity of the UAG-decoding tRNA. The result reveals the unexpected flexibility of the genetic code.

Mukai, Takahito; Hayashi, Akiko; Iraha, Fumie; Sato, Aya; Ohtake, Kazumasa; Yokoyama, Shigeyuki; Sakamoto, Kensaku

2010-01-01

321

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

322

Physical map of the Escherichia coli K12 genome  

SciTech Connect

A physical map of a genome is the structure of its DNA. Construction of such a map is a first step in the complete characterization of that DNA. The restriction endonuclease Not I cuts the genome of Escherichia coli K12 into 22 DNA fragments ranging from 20 kilobases (20,000 base pairs) to 1000 kilobases. These can be separated by pulsed field gel electrophoresis. The order of the fragments in the genome was determined from available E. coli genetic information and analysis of partial digest patterns. The resulting ordered set of fragments is a macrorestriction map. This map facilitates genetic and molecular studies on E. coli, and its construction serves as a model for further endeavors on larger genomes.

Smith, C.L.; Econome, J.G.; Schutt, A.; Klco, S.; Cantor, C.R.

1987-06-12

323

Functions of the gene products of Escherichia coli.  

PubMed Central

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

Riley, M

1993-01-01

324

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

PubMed

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

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

2011-09-28

325

Preparation of soluble proteins from Escherichia coli.  

PubMed

Purification of human IL-1beta is used in this unit as an example of the preparation of soluble proteins from E. coli. Bacteria containing IL-1beta are lysed, and IL-1 beta in the resulting supernatant is purified by anion-exchange chromatography, salt precipitation and cation-exchange chromatography, and then concentrated. Finally, the IL-1 beta protein is applied to a gel-filtration column to separate it from remaining higher- and lower-molecular-weight contaminants, the purified protein is stored frozen or is lyophilized. The purification protocol described is typical for a protein that is expressed in fairly high abundance (i.e., >5% total protein) and accumulates in a soluble state. PMID:18429289

Wingfield, Paul T

2005-09-01

326

The metabolism of isocytidine in Escherichia coli  

PubMed Central

Intact cells and cell-free extracts of E. coli convert isocytidine to isocytosine and uracil. The radioactive label of 5-[3H]isocytidine is incorporated into RNA and, DNA of growing bacteria at a rate equal to about 1.4% of that of cytidine under similar conditions; the radioactivity is found in uridylic, cytidylic and 2?-deoxythymidylic acids, while less than 0.4% of incorporated radioactive material might be due to possible incorporation of intact isocytidine. Uridine phosphorylase and cytidine deaminase apparently do not participate in the metabolic conversion of isocytidine. 5-[3H]isocytidine was prepared by platinum-catalyzed dehalogenation of 5-bromoisocytidine in the presence of tritium. The 5-bromo derivative was obtained from 2?,3?-0- -isopropylideneisocytidine by N-bromsuccinimide bromination followed by acidic hydrolysis.

Doskocil, J.; Holy, A.; Filip, J.

1974-01-01

327

Sensitivity testing of a coupled Escherichia coli Hydrologic catchment model  

NASA Astrophysics Data System (ADS)

A conceptual model of microbial behaviour in catchments coupled with a standard hydrological model, known as the EG model, has been previously developed and tested for Escherichia coli. Due to the unavailability of pathogen data, E. coli has been used as a pathogen indicator. However, the model uses a broad conceptual approach and therefore should be tested for other microbes in future. This paper presents work done on sensitivity of the EG model, as well as its further refinement. Sensitivity of the model results to all E. coli calibration parameters was carried out. The EG model was then tested for its sensitivity to the number of events used to calibrate the model. The data collected at three different Australian drinking water catchments were used. Of the four parameters in the E. coli component of the EG model, two proved to be insensitive while the other two proved to be important. The sensitive parameters were the coefficients associated with the ‘wash-off’ functions in the model, while the two insensitive coefficients were associated with the E. coli decay functions in the model. However, the model became more sensitive towards the decay parameters in cleaner catchments. This indicates that the hydrologic aspects of the E. coli transport processes dominate rather than the E. coli decay functions. Apart from one catchment (that was partly urbanised and much smaller than the other two), the model was successfully calibrated using a small number of monitored events. It was concluded that the EG model could be simplified further by not modelling the decay of the pathogen indicator, E. coli.

Haydon, S.; Deletic, A.

2007-05-01

328

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

329

Two-component nature of bacteriophage T4 receptor activity in Escherichia coli K-12.  

PubMed Central

Escherichia coli bacteriophage T4 uses the lipopolysaccharide of the outer cell envelope membrane as a receptor. Lipopolysaccharide from E. coli K-12 required a major outer membrane protein, polypeptide Ib, for phage inactivation.

Henning, U; Jann, K

1979-01-01

330

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

331

Rapid PCR detection of enterohemorrhagic Escherichia coli (EHEC) in bovine food products and feces  

Microsoft Academic Search

Although Escherichia coli (E. coli) O157:H7 is a major cause of foodborne illness, other types of E. coli can also cause illness. E. coli that possess the eae gene for attachment and effacing have the potential to cause disease. Many real-time, molecular-based assays have been developed to detect Enterohemorrhagic E. coli (EHEC) including E. coli O157:H7. However, no assay currently

Jay L. E. Ellingson; Jeff J. Koziczkowski; Jennifer L. Anderson; Steve A. Carlson; Vijay K. Sharma

2005-01-01

332

Fimbriation and curliation in Escherichia coli O157  

PubMed Central

Shiga toxin-producing Escherichia coli (STEC) serotypes, particularly E. coli O157:H7, possess a variety of fimbrial and afimbrial adhesins which have emerged as important contributors to intestinal colonization. E. coli O157:H7 possesses two chromosomal operons encoding long polar fimbriae (Lpf), which have been found to influence adherence in vitro and colonization in vivo. In a recent Infection and Immunity paper, we further explored the role of Lpf in E. coli O157:H7 intestinal colonization by using the infant rabbit model of STEC infection. We found that an E. coli O157:H7 Lpf-deficient mutant was outcompeted in the rabbit intestine by its parental strain, which may suggest that Lpf contributes to colonization. In contrast, the Lpf-deficient mutant showed an increased adherence to cultured intestinal epithelial cells, and we discovered that this strain overexpressed curli fibers. In this addendum article, we provide a continued perspective on the predicted roles of Lpf and curli, both in vivo and in vitro.

Lloyd, Sonja J.; Ritchie, Jennifer M.; Torres, Alfredo G.

2012-01-01

333

Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance.  

PubMed

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

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

2013-08-14

334

Unusual "flesh-eating" strains of Escherichia coli.  

PubMed

Monomicrobial necrotizing fasciitis (type II) is typically caused by group A streptococcus alone or in combination with Staphylococcus aureus. Escherichia coli has been isolated from polymicrobial or Fournier's gangrene but has rarely been reported in monomicrobial necrotizing fasciitis. We describe the clinical characteristics and outcomes of seven cases of monomicrobial E. coli necrotizing fasciitis and/or severe soft tissue infection diagnosed at a single institution during an 18-month period. Four isolates from three patients and two isolates from two patients with type I polymicrobial severe soft tissue infection (controls) were assayed by the randomly amplified polymorphic DNA (RAPD) analysis for fingerprinting and PCR amplification of primers in order to detect cytotoxic necrotizing factor 1 and 2 (cnf1 and cnf2) genes. All patients had some type of immune suppression. The limb was the most commonly involved organ. In all cases, E. coli was isolated as a monomicrobial pathogen from blood, fascia, or both. All patients died during hospitalization, three within the first 48 h. The RAPD amplification assay showed a high degree of genetic diversity among the "flesh-eating" strains and controls. The cnf1 toxin gene was identified in two out of three cases, but not in the controls. cnf2 was not detected in any of the patients. E. coli may be responsible for life-threatening necrotizing fasciitis. Further research is needed to reveal relevant risk factors, reservoirs, and modes of transmission of cnf1 E. coli. PMID:23035196

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

2012-10-03

335

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

336

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

337

Canine feces as a reservoir of extraintestinal pathogenic Escherichia coli.  

PubMed

To test the canine reservoir hypothesis of extraintestinal pathogenic Escherichia coli (ExPEC), 63 environmental canine fecal deposits were evaluated for the presence of ExPEC by a combination of selective culturing, extended virulence genotyping, hemagglutination testing, O serotyping, and PCR-based phylotyping. Overall, 30% of canine fecal samples (56% of those that yielded viable E. coli) contained papG-positive E. coli, usually as the predominant E. coli strain and always possessing papG allele III (which encodes variant III of the P-fimbrial adhesin molecule PapG). Multiple other virulence-associated genes typical of human ExPEC were prevalent among the canine fecal isolates. According to serotyping, virulence genotyping, and random amplified polymorphic DNA analysis, over 50% of papG-positive fecal E. coli could be directly correlated with specific human clinical isolates from patients with cystitis, pyelonephritis, bacteremia, or meningitis, including archetypal human ExPEC strains 536, CP9, and RS218. Five canine fecal isolates and (clonally related) archetypal human pyelonephritis isolate 536 were found to share a novel allele of papA (which encodes the P-fimbrial structural subunit PapA). These data confirm that ExPEC representing known virulent clones are highly prevalent in canine feces, which consequently may provide a reservoir of ExPEC for acquisition by humans. PMID:11179292

Johnson, J R; Stell, A L; Delavari, P

2001-03-01

338

Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance  

PubMed Central

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

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

2013-01-01

339

Environmental factors affecting indole production in Escherichia coli.  

PubMed

A variety of both Gram-positive and Gram-negative bacteria produce large quantities of indole as an intercellular signal in microbial communities. Biosynthesis of indole is well-studied, and while carbon sources and amino acids are important environmental cues for indole production in Escherichia coli, other environmental factors affecting indole production for this strain are less clear. This study demonstrates that the environmental cue pH is an important factor for indole production that further controls biofilm formation of E. coli. Moreover, E. coli produced a higher level of extracellular indole in the presence of the antibiotics ampicillin and kanamycin, and the increased indole enhanced cell survival during antibiotic stress. Additionally, we found here that temperature is another important factor for indole production; E. coli produces and accumulates a large amount of indole at 50 °C, even at low cell densities. Overall, our results suggest that indole is a stable biological compound, and E. coli may utilize indole to protect itself against other microorganisms. PMID:21145393

Han, Thi Hiep; Lee, Jin-Hyung; Cho, Moo Hwan; Wood, Thomas K; Lee, Jintae

2010-12-08

340

Environmental Factors Affecting Indole Production in Escherichia coli  

PubMed Central

A variety of both Gram-positive and Gram-negative bacteria produce large quantities of indole as an intracellular signal in microbial communities. Biosynthesis of indole is well-studied, and while carbon sources and amino acids are important environmental cues for indole production in Escherichia coli, other environmental factors affecting indole production for this strain are less clear. This study demonstrates that the environmental cue pH is an important factor for indole production that further controls biofilm formation of E. coli. Moreover, E. coli produced a higher level of extracellular indole in the presence of the antibiotics ampicillin and kanamycin, and the increased indole enhanced cell survival during antibiotic stress. Additionally, we found here that temperature is another important factor for indole production; E. coli produces and accumulates a large amount of indole at 50°C, even at low cell densities. Overall, our results suggest that indole is a stable biological compound, and E. coli may utilize indole to protect itself against other microorganisms.

Han, Thi Hiep; Lee, Jin-Hyung; Cho, Moo Hwan; Wood, Thomas K.; Lee, Jintae

2011-01-01

341

The distribution and genetic structure of Escherichia coli in Australian vertebrates: host and geographic effects  

Microsoft Academic Search

Escherichia coli was isolated from more than 2300 non-domesticated vertebrate hosts living in Australia. E. coli was most prevalent in mammals, less prevalent in birds and uncommon in fish, frogs and reptiles. Mammals were unlikely to harbour E. coli if they lived in regions with a desert climate and less likely to have E. coli if they lived in the

David M. Gordon; Ann Cowling

2003-01-01

342

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

343

The fate of Escherichia coli O157 in soil and its potential to contaminate drinking water  

Microsoft Academic Search

The survival and transport of Escherichia coli and E. coli O157 after cattle slurry application were studied on drained plots in both grassland and arable stubble at three sites in Scotland. Leaching losses were between 0.2% and 10% of total E. coli and were dependent on rainfall. Recovery of E. coli in grass and soil declined with approximately first order

Iain D Ogden; David R Fenlon; Andrew J. A Vinten; Douglas Lewis

2001-01-01

344

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

345

ELECTRON-TRANSPORT COMPONENTS OF STREPTOMYCIN-DEPENDENT ESCHERICHIA COLI  

PubMed Central

Bragg, P. D. (University of British Columbia, Vancouver, B. C, Canada) and W. J. Polglase. Electron-transport components of streptomycin-dependent Escherichia coli. J. Bacteriol. 86:544–547. 1963.—When a streptomycin-dependent strain of Escherichia coli was grown in antibiotic-free medium, the resulting streptomycin-depleted cells were found to contain relatively large amounts of vitamin K2. Cytochromes a1 and a2 were absent from depleted cells, and these cells metabolized glucose with the accumulation of lactic acid. Depleted cells were normal in their content of coenzyme Q8, total flavine, and cytochrome b. Growth of depleted cells on medium containing dihydrostreptomycin restored their ability to metabolize lactic acid concomitantly with a decrease in vitamin K2 to a normal level, and with the formation of cytochromes a1 and a2. It is concluded that streptomycin (or dihydrostreptomycin) is required by dependent E. coli for maintenance of the integrity of the electron-transport system.

Bragg, P. D.; Polglase, W. J.

1963-01-01

346

Role of enteroaggregative Escherichia coli virulence factors in uropathogenesis.  

PubMed

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. PMID:23357383

Boll, Erik J; Struve, Carsten; Boisen, Nadia; Olesen, Bente; Stahlhut, Steen G; Krogfelt, Karen A

2013-01-28

347

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

348

Ultraviolet Radiation Studies of Filamentous Escherichia coli B  

PubMed Central

Kantor, George J. (The Pennsylvania State University, University Park), and R. A. Deering. Ultraviolet radiation studies of filamentous Escherichia coli B. J. Bacteriol. 92:1062–1069. 1966.—Small ultraviolet (UV) doses cause Escherichia coli B to grow into long filamentous single cells. A large fraction of these filaments can recover their division ability and can form colonies under appropriate conditions. Preformed filaments can be irradiated with UV, and their ability to still produce colonies can be compared with that of irradiated normal cells. In this regard, filaments are more sensitive to UV than normal cells. Filaments can still host-cell reactivate UV-irradiated T1 phage and can regain their own deoxyribonucleic acid (DNA) synthetic ability after it has been blocked by UV. This indicates that these filaments still retain mechanisms for repairing UV-damaged DNA. Pantoyl lactone, an agent that stimulates cell-division recovery in UV-irradiated E. coli B, causes increased UV resistance for both normal and filamentous cells, with the filaments becoming more resistant than normal cells. In the absence of pantoyl lactone, irradiated filaments grow to a length of about 50 times normal and then stop growing. These long filaments cannot subsequently divide and give colonies. We conclude that the UV dose given to the preformed filaments causes an additional division lag beyond that of unirradiated filaments, and that some critical length is reached after which division recovery and colony formation is impossible. Irradiated normal cells recover before reaching this critical length.

Kantor, George J.; Deering, R. A.

1966-01-01

349

Effect of bile on growth, peritoneal absorption, and blood clearance of Escherichia coli in E coli peritonitis.  

PubMed

The effect of intraperitoneal bile on growth, peritoneal absorption, and clearance of Escherichia coli was determined in E coli peritonitis in the rat. In E coli peritonitis, intraperitoneal bacterial counts gradually decreased, whereas they increased (after 2 hours) with subsequent development of bacteremia in E coli plus bile peritonitis. After an intraperitoneal injection of labeled bacteria, blood radioactivity was only initially lower in E coli plus bile peritonitis compared with E coli peritonitis. Clearance from blood was lower in E coli plus bile peritonitis than in E coli peritonitis. Organ localization was similar in E coli peritonitis and E coli plus bile peritonitis with decreased splenic, increased pulmonary, and unchanged hepatic uptakes compared with controls. Impaired peritoneal absorption of bacteria, together with impaired local host defense, is likely to enhance the noxious effect of bile in E coli peritonitis. PMID:2039367

Andersson, R; Schalén, C; Tranberg, K G

1991-06-01

350

[Escherichia coli salpingitis and peritonitis in layer chickens: an overview].  

PubMed

Escherichia coli can induce salpingitis and/or peritonitis, a major cause of mortality in layer hens, but also other localized and systemic infections. E. coli infections have also been described in turkeys, geese, and ducks and are thought to be the cause of significant economic losses. However little is known about the real economic impact of the disease in layer chickens. The pathogenesis of E. coli salpingitis and peritonitis has not been elucidated yet. Three routes of infection have been discussed in the literature: ascending faecal contamination from the cloaca, bacterial translocation from the respiratory tract (air sac and lungs) and bacterial translocation from the intestinal lumen. Only one study has reported the occurrence of ascending faecal contamination from the cloaca to the oviduct and subsequently to the peritoneum. Regarding bacterial translocation, the only models available are for mammals, and these have not been applied to chickens so far Animal models could prove valuable to elucidate the pathogenesis of E. coli-induced salpingitis and peritonitis, and for assessing the value of preventive and curative intervention strategies. Little is known about risk factors for E. coli salpingitis and peritonitis. In contrast to colibacillosis in broilers, recent research has failed to demonstrate an association between several pathogens of the respiratory tract and the occurrence of E. coli pathology in layer chickens. The distance between poultry farms and the hen density in the cages were recently proposed as important risk factors for outbreaks ofcolibacillosis in flocks of layer hens, while in the past hormonal factors were implicated. The latter is an area of research that deserves more attention. Several methods for the molecular typing of E. coli have been described and might prove useful to study the epidemiology ofE. coli outbreaks in poultry, about which little is known. The presumptive diagnosis E. coli salpingitis and peritonitis is rather simple to establish, based on the anamnesis, clinical symptoms, and macroscopic findings at post-mortem. However; bacteriological analysis is required to establish a definite diagnosis because other pathogens can also cause salpingitis and peritonitis in layer hens. Antibiotics, chosen on the basis of sensitivity testing and their pharmacokinetic properties can be used as therapy; however residues in eggs may occur. Autovaccines are often used as prevention because in practice effective protection is only achieved against homologous E. coli serotypes. PMID:17263015

Landman, W J M; Cornelissen, R A

2006-11-15

351

The adherence of Escherichia coli mutants to mouse splenic lymphocytes  

PubMed Central

Strains of Escherichia coli that do not bind to lymphocytes can be converted to lymphocyte-binding strains by selecting for bacteriophage resistance. The mutants appear to fall into three classes: those whose binding can be inhibited by mannose, those whose binding can be inhibited by charged molecules, and those whose binding cannot be inhibited by either simple sugars or by charged molecules. The mannose-inhibitable mutants may bind via a bacterial lectin whereas the other mutants may bind via ionic interactions. Selection for phage resistance provides a simple way to obtain bacterial strains that bind to lymphocytes, which should facilitate the elucidation of the mechanism by which lymphocytes and bacteria interact.

Mayer, E. P.

1984-01-01

352

Metabolic engineering for advanced biofuels production from Escherichia coli.  

PubMed

Global energy and environmental problems have stimulated increasing efforts toward 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. PMID:18761088

Atsumi, Shota; Liao, James C

2008-09-12

353

Growth kinetics of Colpoda steinii on Escherichia coli.  

PubMed

Colpoda steinii was grown in two-stage continuous cultures with Escherichia coli as prey species. The concentration of prey and the ciliate mean cell volume, dry weight, and number per milliliter were determined at known growth rates. Steady states were reached in the second-stage continuous cultures at all growth rates. Although changes occurred in mean cell size of the ciliates and in the number per milliliter at various growth rates, the yield of protozoan biomass per unit of prey consumed was constant at all growth rates. The data were compared with several equations proposed to describe the kinetics of protozoan growth as a function of prey density. PMID:407843

Drake, J F; Tsuchiya, H M

1977-07-01

354

Growth kinetics of Colpoda steinii on Escherichia coli.  

PubMed Central

Colpoda steinii was grown in two-stage continuous cultures with Escherichia coli as prey species. The concentration of prey and the ciliate mean cell volume, dry weight, and number per milliliter were determined at known growth rates. Steady states were reached in the second-stage continuous cultures at all growth rates. Although changes occurred in mean cell size of the ciliates and in the number per milliliter at various growth rates, the yield of protozoan biomass per unit of prey consumed was constant at all growth rates. The data were compared with several equations proposed to describe the kinetics of protozoan growth as a function of prey density.

Drake, J F; Tsuchiya, H M

1977-01-01

355

Structure of the Escherichia coli S10 ribosomal protein operon.  

PubMed Central

The complete structure of the Escherichia coli S10 ribosomal protein operon is presented. Based on the DNA sequence, the deduced order of the 11 genes in the operon is rpsJ, rplC, rplD, rplW, rplB, rpsS, rplV, rpsC, rplP, rpmC, rpsQ. The estimated transcribed length of the operon is 5181 base pairs. Putative sequences involved in ribosome binding are discussed. The DNA sequence data corrects several errors in previously determined protein sequence data.

Zurawski, G; Zurawski, S M

1985-01-01

356

Expression of Clostridium acetobutylicum butanol synthetic genes in Escherichia coli  

Microsoft Academic Search

A recombinant butanol pathway composed of Clostridium acetobutylicum ATCC 824 genes, thiL, hbd, crt, bcd-etfB-etfA, and adhe1 (or adhe) coding for acetyl-CoA acetyltransferase (THL), ?-hydroxybutyryl-CoA dehydrogenase (HBD), 3-hydroxybutyryl-CoA dehydratase\\u000a (CRT), butyryl-CoA dehydrogenase (BCD), butyraldehyde dehydrogenase (BYDH), and butanol dehydrogenase (BDH), under the tac promoter control was constructed and was introduced into Escherichia coli. The functional expression of these six enzymes

Masayuki Inui; Masako Suda; Sakurako Kimura; Kaori Yasuda; Hiroaki Suzuki; Hiroshi Toda; Shogo Yamamoto; Shohei Okino; Nobuaki Suzuki; Hideaki Yukawa

2008-01-01

357

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

358

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

359

Global Properties of the Metabolic Map of Escherichia coli  

PubMed Central

The EcoCyc database characterizes the known network of Escherichia coli small-molecule metabolism. Here we present a computational analysis of the global properties of that network, which consists of 744 reactions that are catalyzed by 607 enzymes. The reactions are organized into 131 pathways. Of the metabolic enzymes, 100 are multifunctional, and 68 of the reactions are catalyzed by >1 enzyme. The network contains 791 chemical substrates. Other properties considered by the analysis include the distribution of enzyme subunit organization, and the distribution of modulators of enzyme activity and of enzyme cofactors. The dimensions chosen for this analysis can be employed for comparative functional analysis of complete genomes.

Ouzounis, Christos A.; Karp, Peter D.

2000-01-01

360

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

361

Causes, prevention and treatment of Escherichia coli infections.  

PubMed

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

Gould, Dinah

362

Intracellular location of the histonelike protein HU in Escherichia coli.  

PubMed Central

Immunocytochemical labeling of thin sections of cryosubstituted, Lowicryl-embedded Escherichia coli cells with protein A-colloidal gold was used to study the structural organization of the bacterial nucleoid. We found that the histonelike protein HU was not associated with the bulk DNA in the nucleoid but was located in areas of the cell where metabolically active DNA is associated with ribosomes and where single-stranded DNA, RNA polymerase, and DNA topoisomerase I were also located. The resolution of the methods used did not allow us to decide whether HU was associated either with ribosomes or with transcriptionally active DNA, nor could we demonstrate interaction of HU with either. Images

Durrenberger, M; Bjornsti, M A; Uetz, T; Hobot, J A; Kellenberger, E

1988-01-01

363

Superoxide protects Escherichia coli from bleomycin mediated lethality.  

PubMed

Superoxide and its products, especially hydroxyl radical, were recently proposed to be instrumental in cell death following treatment with a wide range of antimicrobials. Surprisingly, bleomycin lethality to Escherichia coli was ameliorated by a genetic deficiency of superoxide dismutase or by furnishing the superoxide generator plumbagin. Rescue by plumbagin was similar in strains containing or lacking recA or with inactive, inducible, or constitutive soxRS regulons. Thus, superoxide interferes with bleomycin cytotoxicity in ways not readily explained by genetic pathways expected to protect from oxidative damage. PMID:19679357

Burger, Richard M; Drlica, Karl

2009-07-17

364

Unique and overlapping pollutant stress proteins of Escherichia coli.  

PubMed Central

Exposure of growing batch cultures of Escherichia coli to nine different "model micropollutants" (benzene, cadmium chloride, chlorpyrivos, 2,4-dichloroaniline, dioctylphtalate, 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. Images

Blom, A; Harder, W; Matin, A

1992-01-01

365

Engineering Escherichia coli for improved ethanol production from gluconate.  

PubMed

We report on engineering Escherichia coli to produce ethanol at high yield from gluconic acid (gluconate). Knocking out genes encoding for the competing pathways (l-lactate dehydrogenase and pyruvate formate lyase A) in E. coli KO11 eliminated lactate production, lowered the carbon flow toward acetate production, and improved the ethanol yield from 87.5% to 97.5% of the theoretical maximum, while the growth rate of the mutant strain was about 70% of the wild type. The corresponding genetic modifications led to a small improvement of ethanol yield from 101.5% to 106.0% on glucose. Deletion of the pyruvate dehydrogenase gene (pdh) alone improved the ethanol yield from 87.5% to 90.4% when gluconate was a substrate. The growth rate of the mutant strain was identical to that of the wild type. The corresponding genetic modification led to no improvements on ethanol yield on glucose. PMID:23942377

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

2013-08-11

366

Cellulosic hydrolysate toxicity and tolerance mechanisms in Escherichia coli  

PubMed Central

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

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

2009-01-01

367

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

368

Engineered polyketide biosynthesis and biocatalysis in Escherichia coli  

PubMed Central

Polyketides are important bioactive natural products biosynthesized by bacteria, fungi, and plants. The enzymes that synthesize polyketides are collectively referred to as polyketide synthases (PKSs). Because many of the natural hosts that produce polyketides are difficult to culture or manipulate, establishing a universal heterologous host that is genetically tractable has become an important goal toward the engineered biosynthesis of polyketides and analogues. Here, we summarize the recent progresses in engineering Escherichia coli as a heterologous host for reconstituting PKSs of different types. Our increased understanding of PKS enzymology and structural biology, combined with new tools in protein engineering, metabolic engineering, and synthetic biology, has firmly established E. coli as a powerful host for producing polyketides.

Gao, Xue; Wang, Peng

2010-01-01

369

Escherichia coli and Community-acquired Gastroenteritis, Melbourne, Australia  

PubMed Central

As part of a study to determine the effects of water filtration on the incidence of community-acquired gastroenteritis in Melbourne, Australia, we examined fecal samples from patients with gastroenteritis and asymptomatic persons for diarrheagenic strains of Escherichia coli. Atypical strains of enteropathogenic E. coli (EPEC) were the most frequently identified pathogens of all bacterial, viral, and parasitic agents in patients with gastroenteritis. Moreover, atypical EPEC were more common in patients with gastroenteritis (89 [12.8%] of 696) than in asymptomatic persons (11 [2.3%] of 489, p < 0.0001). Twenty-two random isolates of atypical EPEC that were characterized further showed marked heterogeneity in terms of serotype, genetic subtype, and carriage of virulence-associated determinants. Apart from the surface protein, intimin, no virulence determinant or phenotype was uniformly present in atypical EPEC strains. This study shows that atypical EPEC are an important cause of gastroenteritis in Melbourne.

Bordun, Anne-Marie; Tauschek, Marija; Bennett-Wood, Vicki R.; Russell, Jacinta; Oppedisano, Frances; Lister, Nicole A.; Bettelheim, Karl A.; Fairley, Christopher K.; Sinclair, Martha I.; Hellard, Margaret E.

2004-01-01

370

Genetic characterization of moaB mutants of Escherichia coli.  

PubMed

The moaABCDE operon of Escherichia coli encodes enzymes essential for the biosynthesis of the molybdenum cofactor (Moco). However, the role of the moaB gene within this operon has remained enigmatic. Here, we have investigated the effect of moaB defects on two phenotypes diagnostic for Moco-deficiency: chlorate-resistance and sensitivity to the base analog 6-N-hydroxylaminopurine (HAP). We found that transposon insertions in moaB caused partial Moco-deficiency associated with chlorate-resistance, but not for HAP-sensitivity. On the other hand, in-frame deletions of moaB, or moaB overexpression, had no effect on either phenotype. Our combined data are consistent with the lack of any role for MoaB in Moco biosynthesis in E. coli. PMID:23680484

Kozmin, Stanislav G; Schaaper, Roel M

2013-05-13

371

Butyrate production in engineered Escherichia coli with synthetic scaffolds.  

PubMed

Butyrate pathway was constructed in recombinant Escherichia coli using the genes from Clostridium acetobutylicum and Treponema denticola. However, the pathway constructed from exogenous enzymes did not efficiently convert carbon flux to butyrate. Three steps of the productivity enhancement were attempted in this study. First, pathway engineering to delete metabolic pathways to by-products successfully improved the butyrate production. Second, synthetic scaffold protein that spatially co-localizes enzymes was introduced to improve the efficiency of the heterologous pathway enzymes, resulting in threefold improvement in butyrate production. Finally, further optimizations of inducer concentrations and pH adjustment were tried. The final titer of butyrate was 4.3 and 7.2?g/L under batch and fed-batch cultivation, respectively. This study demonstrated the importance of synthetic scaffold protein as a useful tool for optimization of heterologous butyrate pathway in E. coli. Biotechnol. Bioeng. 2013;110: 2790-2794. © 2013 Wiley Periodicals, Inc. PMID:23568786

Baek, Jang-Mi; Mazumdar, Suman; Lee, Sang-Woo; Jung, Moo-Young; Lim, Jae-Hyung; Seo, Sang-Woo; Jung, Gyoo-Yeol; Oh, Min-Kyu

2013-04-22

372

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

PubMed

A three-dimensional structural model of Escherichia coli fructosamine 6-kinase (FN6K), an enzyme that phosphorylates fructosamines at C6 and catalyzes the production of the fructosamine 6-phosphate stable intermediate, was generated using the crystal structure of 2-keto-3-deoxygluconate kinase isolated from Thermus thermophilus as template. The putative active site region was then investigated by site-directed mutagenesis to reveal several amino acid residues that likely play important roles in the enzyme reaction. Met220 was identified as a residue that plays a role in substrate recognition when compared to Bacillus subtilis derived FN6K, which shows different substrate specificity from the E. coli FN6K. Among the various Met220-substituted mutant enzymes, Met220Leu, which corresponded to the B. subtilis residue, resulted in an increased activity of fructosyl-valine and decreased activity of fructosyl-lysine, thus increasing the specificity for fructosyl-valine by 40-fold. PMID:23076362

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

2012-10-18

373

Inner membrane lipids of Escherichia coli form domains.  

PubMed

In prokaryotic cells, the hypothesis of the existence of lipid domains was considered. In order to test this hypothesis and study the organization of lipids in the inner membrane of Escherichia coli, we elaborated Langmuir films mimicking the inner leaflet of this membrane by considering lipids extracted from the inner membrane of E coli by Folch protocol. Lipid monolayers were elaborated by using these extracts (Langmuir technique); the organization of the resulting films was studied at the air-water interface by Brewster angle microscopy and after transfer onto muscovite by atomic force microscopy. The existence of domains was demonstrated for different interfacial pressures of biological interest, and their stability was studied. PMID:18243672

Zerrouk, Zakia; Alexandre, Stéphane; Lafontaine, Céline; Norris, Vic; Valleton, Jean-Marc

2008-01-04

374

Phenotypic and genotypic characterization of human and nonhuman Escherichia coli.  

PubMed

Estuarine waters receive fecal pollution from a variety of sources, including humans and wildlife. Escherichia coli is one of several fecal coliform bacteria that inhabit the intestines of many warm-blooded animals that sometimes contaminate water. Its presence does not specifically implicate human fecal input, therefore it is necessary to differentiate contamination sources to accurately assess health risks. E. coli were isolated from human sources (HS) and nonhuman sources (NHS) in the Apalachicola National Estuarine Research Reserve and analyzed for fatty acid methyl ester (FAME), O-serogroup, and pulsed-field gel electrophoresis (PFGE) profiles. For FAME and PFGE analyses, there was no relationship between profile and isolate source. Human source PFGE profiles were less diverse than NHS isolates, and conversely for FAME. In contrast, O-serogrouping showed less diversity for HS vs. NHS isolates, and the predominant HS O-serogroups differed significantly (P < 0.01) from those of NHS isolates. PMID:11228989

Parveen, S; Hodge, N C; Stall, R E; Farrah, S R; Tamplin, M L

2001-02-01

375

Continuous-sterilization system that uses photosemiconductor powders. [Escherichia coli  

SciTech Connect

We report a novel photochemical sterilization system in which Escherichia coli cells were sterilized with photosemiconductor powders (titanium oxide). For sterilization that could be used in practice, it was necessary to separate the TiO/sub 2/ powders from the cell suspension. Therefore, semiconductor powders were immobilized on acetylcellulose membranes. We constructed a continuous-sterilization system consisting of TiO/sub 2/-immobilized acetylcellulose membrane reactor, a mercury lamp, and a masterflex pump. As a result, under the various sterilization conditions examined, E.coli (10/sup 2/ cells per ml) was sterilized to < 1% survival when the cell suspension flowed in this system at a mean residence time of 16.0 min under irradiation (1800 microeinsteins/m/sup 2/ per s). We found that this system was reusable.

Matsunaga, T.; Tomoda, R.; Nakajima, T.; Nakamura, N.; Komine, T.

1988-06-01

376

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

2011-12-10

377

Isolation and characterization of isoprene mutants of Escherichia coli.  

PubMed Central

Isoprenoid compounds are found in all organisms. In Escherichia coli the isoprene pathway has three distinct branches: the modification of tRNA; the respiratory quinones ubiquinone and menaquinone; and the dolichols, which are long-chain alcohols involved in cell wall biosynthesis. Very little is known about procaryotic isoprene biosynthesis compared with what is known about eucaryote isoprene biosynthesis. This study approached some of the questions about isoprenoid biosynthesis and regulation in procaryotes by isolating and characterizing mutants in E. coli. Mutants were selected by determining their resistance to low levels of aminoglycoside antibiotics, which require an electron transport chain for uptake into bacterial cells. The mutants were characterized with regard to their phenotypes, map positions, enzymatic activities, and total ubiquinone content. In particular, the enzymes studied were isopentenyldiphosphate delta-isomerase (EC 5.3.3.2), farnesyldiphosphate synthetase (EC 2.5.1.1), and higher prenyl transferases.

Sherman, M M; Petersen, L A; Poulter, C D

1989-01-01

378

The complete genome sequence of Escherichia coli K-12.  

PubMed

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

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

1997-09-01

379

Evolution of Escherichia coli for growth at high temperatures.  

PubMed

Evolution depends on the acquisition of genomic mutations that increase cellular fitness. Here, we evolved Escherichia coli MG1655 cells to grow at extreme temperatures. We obtained a maximum growth temperature of 48.5 degrees C, which was not increased further upon continuous cultivation at this temperature for >600 generations. Despite a permanently induced heat shock response in thermoresistant cells, only exquisitely high GroEL/GroES levels are essential for growth at 48.5 degrees C. They depend on the presence of lysyl-tRNA-synthetase, LysU, because deletion of lysU rendered thermoresistant cells thermosensitive. Our data suggest that GroEL/GroES are especially required for the folding of mutated proteins generated during evolution. GroEL/GroES therefore appear as mediators of evolution of extremely heat-resistant E. coli cells. PMID:20406805

Rudolph, Birgit; Gebendorfer, Katharina M; Buchner, Johannes; Winter, Jeannette

2010-04-20

380

Identification, expression, and characterization of Escherichia coli guanine deaminase.  

PubMed

Using the human cDNA sequence corresponding to guanine deaminase, the Escherichia coli genome was scanned using the Basic Local Alignment Search Tool (BLAST), and a corresponding 439-residue open reading frame of unknown function was identified as having 36% identity to the human protein. The putative gene was amplified, subcloned into the pMAL-c2 vector, expressed, purified, and characterized enzymatically. The 50.2-kDa protein catalyzed the conversion of guanine to xanthine, having a K(m) of 15 microM with guanine and a k(cat) of 3.2 s(-1). The bacterial enzyme shares a nine-residue heavy metal binding site with human guanine deaminase, PG[FL]VDTHIH, and was found to contain approximately 1 mol of zinc per mol of subunit of protein. The E. coli guanine deaminase locus is 3' from an open reading frame which shows homology to a bacterial purine base permease. PMID:10913105

Maynes, J T; Yuan, R G; Snyder, F F

2000-08-01

381

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

382

Sources of variation of Escherichia coli concentrations in bivalve molluscs.  

PubMed

Bivalve molluscs can concentrate contaminants, including pathogenic microorganisms, from the water column during their normal filter-feeding activity. In the European Union, the risk of human and animal faecal contamination in bivalves is estimated by determining the concentration of Escherichia coli in time-series samples from production areas. A structured field study was undertaken to determine the extent to which such concentrations varied between sites, sampling occasions and shellfish species and to determine the residual variability of the method. E. coli was enumerated in three species of bivalve mollusc (Crassostrea gigas, Mytilus spp. and Pecten maximus) co-located in each of three geographically separate commercial shellfisheries. The data were subjected to analysis of variance (ANOVA). This showed that the effects of site, sampling occasion, species and site/sampling occasion interaction were all significant. The proportion of variation due to site was markedly greater than that due to other factors. Post-ANOVA analysis showed that the concentration of E. coli in P. maximus was significantly higher than in the other two species. Mytilus spp. and C. gigas exhibited comparable levels of E. coli. The observed standard deviation of the most probable number method in the study was 0.33 log(10). PMID:23428551

Lee, R J; Silk, R

2013-03-01

383

Detection of Escherichia coli in meat with an electrochemical biochip.  

PubMed

Detection of foodborne pathogenic and spoilage bacteria by RNA-DNA hybridization is an alternative to traditional microbiological procedures. To achieve high sensitivity with RNA-DNA-based methods, efficient bacterial lysis and release of nucleic acids from bacteria are needed. Here we report the specific detection of the hygiene indicator microorganism Escherichia coli in meat by use of electrochemical biochips. We improved RNA isolation from bacteria in meat juice from pork and beef. Samples, either naturally or artificially contaminated by E. coli, were enriched by incubation in full or minimal medium. A combined treatment of the samples with lysozyme, proteinase K, and sonication resulted in efficient cell disruption and high total RNA yields. Together with optimization of enrichment time, this ensures high sensitivity of electrochemical measurements on biochips. A short enrichment period and the triple-lysis regimen in combination with electrochemical biochip measurement were tested with 25 meat samples. The lower limit of detection of the biochip was approximately 2,000 CFU of E. coli per ml. The entire analysis procedure (5 h of enrichment, triple lysis, and biochip detection) has a lower limit of detection of 1 CFU of E. coli per ml within a total time needed for analysis of 7 h. PMID:21219714

Heidenreich, Bernd; Pöhlmann, Christopher; Sprinzl, Mathias; Gareis, Manfred

2010-11-01

384

Characterization of a second lysine decarboxylase isolated from Escherichia coli.  

PubMed Central

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 lambda 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 and sequenced the homologous region of cadA. This region contained a 2,139-nucleotide open reading frame encoding a 713-amino-acid protein with a calculated molecular weight of 80,589. Overexpression of the protein and determination of its N-terminal amino acid sequence defined the translational start site of this gene. The deduced amino acid sequence showed 69.4% identity to that of lysine decarboxylase encoded by cadA at 93.7 min on the E. coli chromosome. In addition, the level of lysine decarboxylase activity increased in strains carrying multiple copies of the gene. Therefore, the gene encoding this lysine decarboxylase was designated Idc. Analysis of the lysine decarboxylase activity of strains containing cadA, ldc, or cadA ldc mutations indicated that ldc was weakly expressed under various conditions but is a functional gene in E. coli.

Kikuchi, Y; Kojima, H; Tanaka, T; Takatsuka, Y; Kamio, Y

1997-01-01

385

Enteroaggregative Escherichia coli associated with a foodborne outbreak of gastroenteritis.  

PubMed

This study investigated two foodborne outbreaks of gastroenteritis that occurred 10 days apart among individuals who had meals at the restaurant of a farm holiday resort. Mild gastrointestinal symptoms were reported and none of the patients needed hospitalization. Mean incubation times were 45 and 33 h, and the overall attack rates were 43.5 and 58.3%, respectively. Stool sample examination was negative for common enteric pathogens in both outbreaks. Specimens from 13 people involved in the second outbreak and 3 restaurant staff were examined for diarrhoeagenic Escherichia coli. An enteroaggregative E. coli (EAEC) strain of serotype O92:H33 was isolated from six participants and one member of staff. In particular, the EAEC strain was isolated from five of the six cases of diarrhoea examined. The strain showed an aggregative pattern of adherence to HEp-2 cells, did not produce a biofilm and possessed the virulence-related genes aat, aggR, aap and set1A, but not the astA gene. A retrospective cohort study indicated a pecorino cheese made with unpasteurized sheep milk as the possible source (P<0.001). Samples of the cheese had E. coli counts higher than 10(6) c.f.u. g(-1), but the outbreak EAEC strain was not isolated. This report confirms that EAEC infections are probably underdiagnosed because of the limited availability of laboratories capable of identifying this group of pathogenic E. coli. PMID:18719185

Scavia, Gaia; Staffolani, Monica; Fisichella, Stefano; Striano, Gianluca; Colletta, Stefano; Ferri, Giovanni; Escher, Martina; Minelli, Fabio; Caprioli, Alfredo

2008-09-01

386

Transcription, Processing, and Function of CRISPR Cassettes in Escherichia coli  

PubMed Central

CRISPR/Cas, bacterial and archaeal systems of interference with foreign genetic elements such as viruses or plasmids, consist of DNA loci called CRISPR cassettes (a set of variable spacers regularly separated by palindromic repeats) and associated cas genes. When a CRISPR spacer sequence exactly matches a sequence in a viral genome, the cell can become resistant to the virus. The CRISPR/Cas systems function through small RNAs originating from longer CRISPR cassette transcripts. While laboratory strains of Escherichia coli contain a functional CRISPR/Cas system (as judged by appearance of phage resistance at conditions of artificial co-overexpression of Cas genes and a CRISPR cassette engineered to target a ? phage), no natural phage resistance due to CRISPR system function was observed in this best-studied organism and no E. coli CRISPR spacer matches sequences of well-studied E. coli phages. To better understand the apparently “silent” E. coli CRISPR/Cas system, we systematically characterized processed transcripts from CRISPR cassettes. Using an engineered strain with genomically located spacer matching phage ? we show that endogenous levels of CRISPR cassette and cas genes expression allow only weak protection against infection with the phage. However, derepression of the CRISPR/Cas system by disruption of the hns gene leads to high level of protection.

Pougach, Ksenia; Semenova, Ekaterina; Bogdanova, Ekaterina; Datsenko, Kirill A.; Djordjevic, Marko; Wanner, Barry L.; Severinov, Konstantin

2010-01-01

387

A novel endoribonuclease, RNase LS, in Escherichia coli.  

PubMed

The dmd gene of bacteriophage T4 is required for the stability of late-gene mRNAs. When this gene is mutated, late genes are globally silenced because of rapid degradation of their mRNAs. Our previous work suggested that a novel Escherichia coli endonuclease, RNase LS, is responsible for the rapid degradation of mRNAs. In this study, we demonstrated that rnlA (formerly yfjN) is essential for RNase LS activity both in vivo and in vitro. In addition, we investigated a role of RNase LS in the RNA metabolism of E. coli cells under vegetative growth conditions. A mutation in rnlA reduced the decay rate of many E. coli mRNAs, although there are differences in the mutational effects on the stabilization of different mRNAs. In addition, we found that a 307-nucleotide fragment with an internal sequence of 23S rRNA accumulated to a high level in rnlA mutant cells. These results strongly suggest that RNase LS plays a role in the RNA metabolism of E. coli as well as phage T4. PMID:15677746

Otsuka, Yuichi; Yonesaki, Tetsuro

2005-01-01

388

Transcriptome of Uropathogenic Escherichia coli during Urinary Tract Infection  

PubMed Central

A uropathogenic Escherichia coli strain CFT073-specific DNA microarray that includes each open reading frame was used to analyze the transcriptome of CFT073 bacteria isolated directly from the urine of infected CBA/J mice. The in vivo expression profiles were compared to that of E. coli CFT073 grown statically to exponential phase in rich medium, revealing the strategies this pathogen uses in vivo for colonization, growth, and survival in the urinary tract environment. The most highly expressed genes overall in vivo encoded translational machinery, indicating that the bacteria were in a rapid growth state despite specific nutrient limitations. Expression of type 1 fimbriae, a virulence factor involved in adherence, was highly upregulated in vivo. Five iron acquisition systems were all highly upregulated during urinary tract infection, as were genes responsible for capsular polysaccharide and lipopolysaccharide synthesis, drug resistance, and microcin secretion. Surprisingly, other fimbrial genes, such as pap and foc/sfa, and genes involved in motility and chemotaxis were downregulated in vivo. E. coli CFT073 grown in human urine resulted in the upregulation of iron acquisition, capsule, and microcin secretion genes, thus partially mimicking growth in vivo. On the basis of gene expression levels, the urinary tract appears to be nitrogen and iron limiting, of high osmolarity, and of moderate oxygenation. This study represents the first assessment of any E. coli pathotype's transcriptome in vivo and provides specific insights into the mechanisms necessary for urinary tract pathogenesis.

Snyder, Jennifer A.; Haugen, Brian J.; Buckles, Eric L.; Lockatell, C. Virginia; Johnson, David E.; Donnenberg, Michael S.; Welch, Rodney A.; Mobley, Harry L. T.

2004-01-01

389

Biosynthesis of bacterial menaquinones. Menaquinone mutants of Escherichia coli.  

PubMed

The isolation of six menaquinone mutants of Escherichia coli is described. It was shown that the mutants fall into two genetic classes. The first class carries mutations in a gene designated menA, which was located at minute 78 on the E. coli chromosome by cotransduction with the glpK and metB genes. The second class carries mutations in a gene designated menB. It was shown that this gene was not cotransducible with the menA gene. The biosynthesis of menaquinone in E. coli was studied using a variety of mutants blocked in aromatic biosynthesis together with the two classes of menaquinone mutants. It was demonstrated that chorismate is the branch point compound leading to menaquinone, and that 2-succinylbenzoic acid and 1,4-dihydroxy-2-naphthoic acid can serve as menaquinoone precursors in E. coli. It was also shown that menA- and menB- strains accumulate 1,4-dihydroxy-2-naphthoic acid and 2-succinylbenzoic acid, respectively, in their culture supernatants. The accumulation of the two compounds by the mutants together with their activity as menaquinone precursors provide strong evidence that they ar true intermediates in menaquinone biosynthesis. A pathway is proposed for the biosynthesis of bacterial menaquinones in which each intermediate has been adequately characterized. PMID:1091286

Young, I G

1975-01-28

390

Persistence of colicinogenic Escherichia coli in the mouse gastrointestinal tract  

PubMed Central

Background The ability of a bacterial strain to competitively exclude or displace other strains can be attributed to the production of narrow spectrum antimicrobials, the bacteriocins. In an attempt to evaluate the importance of bacteriocin production for Escherichia coli strain residence in the gastrointestinal tract, a murine model experimental evolution study was undertaken. Results Six colicin-producing, yet otherwise isogenic, E. coli strains were administered and established in the large intestine of streptomycin-treated mice. The strains' persistence, population density, and doubling time were monitored over a period of 112 days. Early in the experiment only minor differences in population density between the various colicin-producing and the non-producing control strains were detected. However, over time, the density of the control strains plummeted, while that of the colicin-producing strains remained significantly higher (F(7,66) = 2.317; P < 0.0008). Conclusion The data presented here support prior claims that bacteriocin production may play a significant role in the colonization of E. coli in the gastrointestinal tract. Further, this study suggests that the ability to produce bacteriocins may prove to be a critical factor in determining the success of establishing probiotic E. coli in the gastrointestinal tract of humans and animals.

2009-01-01

391

Detecting Selective Sweeps in Naturally Occurring Escherichia Coli  

PubMed Central

The nucleotide sequences of the gapA and pabB genes (separated by approximately 32.5 kb) were determined in 12 natural isolates of Escherichia coli. Three analyses were performed on the data. First, the levels of polymorphism at the loci were compared within and between E. coli and Salmonella strains relative to their degrees of constraint. Second, the gapA and pabB loci were analyzed by the Hudson-Kreitman-Aguade (HKA) test for selective neutrality. Four additional dispersed genes (crr, putP, trp and gnd) were added to the analysis to provide the necessary frame of reference. Finally, the gene genealogies of gapA and pabB were examined for topological consistency within and between the loci. These lines of evidence indicate that some evolutionary event has recently purged the variability in the region surrounding the gapA and pabB loci in E. coli. This can best be explained by the spread of a selected allele through the global E. coli population by directional selection and the resulting loss in variability in the surrounding regions due to genetic hitchhiking.

Guttman, D. S.; Dykhuizen, D. E.

1994-01-01

392

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

393

Extraintestinal Escherichia coli Carrying Virulence Genes in Coastal Marine Sediments? †  

PubMed Central

Despite the recognized potential of long-term survival or even growth of fecal indicators bacteria (FIB) in marine sediments, this compartment is largely ignored by health protection authorities. We conducted a large-scale study over approximately 50 km of the Marche coasts (Adriatic Sea) at depths ranging from 2 to 5 m. Total and fecal coliforms (FC) were counted by culture-based methods. Escherichia coli was also quantified using fluorescence in situ hybridization targeting specific 16S rRNA sequences, which yielded significantly higher abundances than culture-based methods, suggesting the potential importance of viable but nonculturable E. coli cells. Fecal coliforms displayed high abundances at most sites and showed a prevalence of E. coli. FC isolates (n = 113) were identified by API 20E, additional biochemical tests, and internal transcribed spacer-PCR. E. coli strains, representing 96% of isolates, were then characterized for genomic relatedness and phylogenetic group (A, B1, B2, and D) of origin by randomly amplified polymorphic DNA and multiplex-PCR. The results indicated that E. coli displayed a wide genotypic diversity, also among isolates from the same station, and that 44 of the 109 E. coli isolates belonged to groups B2 and D. Further characterization of B2 and D isolates for the presence of 11 virulence factor genes (pap, sfa/foc, afa, eaeA, ibeA, traT, hlyA, stx1, stx2, aer, and fyuA) showed that 90% of B2 and 65% of D isolates were positive for at least one of these. Most of the variance of both E. coli abundance and assemblage composition (>62%) was explained by a combination of physical-chemical and trophic variables. These findings indicate that coastal sediments could represent a potential reservoir for commensal and pathogenic E. coli and that E. coli distribution in marine coastal sediments largely depends upon the physical and trophic status of the sediment. We conclude that future sampling designs aimed at monitoring the microbiological quality of marine coastal areas should not further neglect the analysis of the sediment and that monitoring of these environments can be improved by including molecular methods as a complement of culture-based techniques.

Luna, G. M.; Vignaroli, C.; Rinaldi, C.; Pusceddu, A.; Nicoletti, L.; Gabellini, M.; Danovaro, R.; Biavasco, F.

2010-01-01

394

Biotipizzazione ed antibioticoresistenza di ceppi d i Escherichia coli isolati da conigli selvatici ( Oryctolagus cuniculus ) asintomatici  

Microsoft Academic Search

Biotyping and antibiotic resistance of Escherichia coli strains isolated from asymptomatic wild rabbits (Oryctolagus cuniculus ). One hundred wild rabbits hunted in Serio Regional Park (Bergamo, Italy) were examinated. Post mortem examination revealed a good body condition, even in rabbits with ecto-endoparasites (Spilopsyllus cuniculi and Cittotaenia spp.). The c aecum of each animal was tested bacteriologically for Escherichia coli. Sixty

G. Grilli; V. Ferrazzi; D. Gallazzi

395

Escherichia coli Bacteriocins: Antimicrobial Efficacy and Prevalence among Isolates from Patients with Bacteraemia  

Microsoft Academic Search

Bacteriocins are antimicrobial peptides generally active against bacteria closely related to the producer. Escherichia coli produces two types of bacteriocins, colicins and microcins. The in vitro efficacy of isolated colicins E1, E6, E7, K and M, was assessed against Escherichia coli strains from patients with bacteraemia of urinary tract origin. Colicin E7 was most effective, as only 13% of the

Maruška Budi?; Matija Rijavec; Živa Petkovšek; Darja Žgur-Bertok

2011-01-01

396

Analysis of Escherichia coli isolates from subjects with travellers' diarrhoea using DNA probes and serotyping  

Microsoft Academic Search

Escherichia coli isolated from faeces of 54 healthy volunteers who visited Tunisia for eight days were examined. These volunteers participated in a randomized doubleblind placebo-controlled study to establish whether ciprofloxacin could prevent travellers' diarrhoea.Escherichia coli strains isolated before travel, during episodes of travellers' diarrhoea, immediately after return and five weeks after return were serotyped and tested for the presence of

C. M. A. Rademaker; M. R. L. Krul; W. H. Jansen; N. M. Vos; I. M. Hoepelman; M. Rozenberg-Arska; J. Verhoef

1991-01-01

397

FACTORS INFLUENCING THE SHEDDING OF ESCHERICHIA COLI AND SALMONELLA SPP. IN HOLSTEIN CATTLE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fecal samples were obtained in replicate from lactating (LAC; n = 60) and non-lactating (NLAC; n = 60) Holstein cows to determine the influence of time of day (AM vs PM), parity, and lactation phase [ 60 d in milk (DIM)] on shedding of Escherichia coli O157:H7 (EHEC), Escherichia coli (EC),...

398

Chemotaxis of Escherichia coli to Pyrimidines: a New Role for the Signal Transducer Tap  

Microsoft Academic Search

Escherichia coli exhibits chemotactic responses to sugars, amino acids, and dipeptides, and the responses are mediated by methyl-accepting chemotaxis proteins (MCPs). Using capillary assays, we demonstrated that Escherichia coli RP437 is attracted to the pyrimidines thymine and uracil and the response was constitutively expressed under all tested growth conditions. All MCP mutants lacking the MCP Tap protein showed no response

Xianxian Liu; Rebecca E. Parales

2008-01-01

399

Association of Enterohemorrhagic Escherichia coli Hemolysin with Serotypes of Shiga-Like-Toxin-Producing Escherichia coli of Human and Bovine Origins  

Microsoft Academic Search

In this study we investigated whether the enterohemorrhagic Escherichia coli (EHEC) hemolysin gene ehxA could be used as an indicator of pathogenicity in Shiga-like-toxin-producing Escherichia coli (SLTEC) isolates. The isolates in a collection of 770 SLTEC strains of human and bovine origins were assigned to group 1 (230 human and 138 bovine SLTEC isolates belonging to serotypes frequently implicated in

CARLTON GYLES; ROGER JOHNSON; ANLI GAO; KIM ZIEBELL; DENIS PIERARD; STOJANKA ALEKSIC; PATRICK BOERLIN

1998-01-01

400

Research on killing Escherichia Coli by reactive oxygen species based on strong ionization discharging plasma  

NASA Astrophysics Data System (ADS)

Reactive oxygen species solution produced by strong ionization discharging plasma was used to kill Escherichia coli by spraying. Several effect factors such as pH value, solution temperature, spraying time and exposure time were observed in this study, and their effects on killing rate of Escherichia coli were discussed and analysed. Results show that the treating efficiency of ROS solution for Escherichia coli is higher in alkaline solution than that in acid solution. The killing rate of Escherichia coli increases while the spraying time and exposure time are longer and the temperature is lower. The effects of different factors on killing rate of Escherichia coli are as follows: spraying time > pH value > exposure time > solution temperature.

Li, Y. J.; Tian, Y. P.; Li, R. H.; Gao, J. Y.; Cai, L. J.; Zhang, Z. T.

2013-03-01

401

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

402

Characterization of Enteropathogenic and Enteroaggregative Escherichia coli Isolated from Diarrheal Outbreaks  

PubMed Central

Virulence characteristics of diarrheal outbreak-associated Escherichia coli O55:NM, O126:NM, and O111:NM were examined. The E. coli O55:NM strains were atypical enteropathogenic E. coli (EPEC), while the E. coli O126:NM and O111:NM strains should be classified as enteroaggregative E. coli (EAggEC). The contributions of EPEC and EAggEC to the human disease burden in Japan might be significantly greater than is currently appreciated.

Yatsuyanagi, Jun; Saito, Shioko; Sato, Hiroyasu; Miyajima, Yoshimichi; Amano, Ken-Ichi; Enomoto, Katsuhiko

2002-01-01

403

Enteroaggregative Escherichia coli an emergent pathogen with different virulence properties.  

PubMed

Enteroaggregative Escherichia coli (EAEC) is an emergent bacterial pathogen. The first studies in developing countries with EAEC strains, showed that this bacterium was associated with persistent diarrhea. However, new studies showed that EAEC may be associated also with acute diarrhea, with both nosocomial and community outbreaks worldwide, and as an important pathogen of diarrheal disease in human immunodeficiency virus-infected adults. EAEC strains are recognized by their characteristic aggregative adherence or "stacked-brick" pattern to epithelial cells. Although the pathogenesis of EAEC infection is not well understood, cellular changes observed in animal models and in vitro assays, suggested that the alterations in the intestinal mucosa during EAEC infection are associated with adherence factors and toxins production. The damage has been associated with the release of inflammatory mediators, which may contribute also to the intestinal illness. The dissemination of the high pathogenicity island from Yersinia pestis evolutionary group to EAEC has been show; different studies suggest that it may contribute to the virulence of EAEC strains. Molecular methods to investigate the presence of plasmid and chromosomal EAEC-associated virulence markers, have been used for the characterization and epidemiological studies of EAEC strains. Although the clinical and epidemiological importance of EAEC have been demonstrated in different studies, Escherichia coli strains with adherent agreggative phenotype are commonly isolated from healthy children and environmental sources. This support the necessity to study virulence factors no related with the cells adherence pattern, that show the specific EAEC pathogenic clones associated whit intestinal disease. PMID:17061538

Villaseca, J M; Hernández, U; Sainz-Espuñes, T R; Rosario, C; Eslava, C

404

Induction of SOS genes of Escherichia coli by chromium compounds  

SciTech Connect

The induction of several SOS genes of Escherichia coli such as recA, umuC, and sfiA by hexavalent (K/sub 2/Cr/sub 2/O/sub 7/, K/sub 2/CrO/sub 4/, and CrO/sub 3/) and trivalent (CrCl/sub 3/, Cr(NO/sub 3/)/sub 3/, and (CH/sub 3/COO)/sub 3/Cr) compounds of chromium was studied. Induction was measured as ..beta..-galactosidase activity, using lacZ gene fusions under the control region of different SOS genes. The hexavalent chromium forms induced the genes responsible for massive synthesis of RecA protein, error-prone repair, and inhibition of cell division. On the other hand, the trivalent chromium compounds were unable to induce any of the SOS genes tested. Individual assay of hexavalent chromium compounds showed that K/sub 2/Cr/sub 2/O/sub 7/ was a stronger inducing agent of those three SOS genes tested than K/sub 2/CrO/sub 4/, which, in turn, was stronger than CrO/sub 3/. All this data led to the conclusion that hexavalent chromium compounds, but not trivalent, are proficient agents of induction of the SOS system and can produce indirect mutagenesis in Escherichia coli.

Llagostera, M.; Garrido, S.; Guerrero, R.; Barbe, J.

1986-01-01

405

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

406

F'-plasmid transfer from Escherichia coli to Pseudomonas fluorescens.  

PubMed Central

Various F' plasmids of Escherichia coli K-12 could be transferred into mutants of the soil strain 6.2, classified herein as a Pseudomonas fluorescens biotype IV. This strain was previously found to receive Flac plasmid (N. Datta and R.W. Hedges, J. Gen Microbiol. 70:453-460, 1972). ilv, leu, met, arg, and his auxotrophs were complemented by plasmids carrying isofunctional genes; trp mutants were not complemented or were very poorly complemented. The frequency of transfer was 10(-5). Subsequent transfer into other P. fluorescens recipients was of the same order of magnitude. Some transconjugants were unable to act as donors, and these did not lose the received information if subcultured on nonselective media. Use of F' plasmids helped to discriminate metabolic blocks in P. fluorescens. In particular, metA, metB, and argH mutants were so distinguished. In addition, F131 plasmid carrying the his operon and a supD mutation could partially relieve the auxotrophy of thr, ilv, and metA13 mutants, suggesting functional expression of E. coli tRNA in P. fluorescens. In P. fluorescens metA Rifr mutants carrying the F110 plasmid, which carried the E. coli metA gene and the E. coli rifs allele, sensitivity to rifampin was found to be dominant at least temporarily over resistance. This suggests interaction of E. coli and P. fluorescens subunits of RNA polymerase. his mutations were also complemented by composite P plasmids containing the his-nif region of Klebsiella pneumoniae (plasmids FN68 and RP41). nif expression could be detected by acetylene reduction in some his+ transconjugants. The frequency of transfer of these P plasmids was 5 X 10(-4).

Mergeay, M; Gerits, J

1978-01-01

407

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

408

Anaerobic Respiration of Escherichia coli in the Mouse Intestine ?  

PubMed Central

The intestine is inhabited by a large microbial community consisting primarily of anaerobes and, to a lesser extent, facultative anaerobes, such as Escherichia coli, which we have shown requires aerobic respiration to compete successfully in the mouse intestine (S. A. Jones et al., Infect. Immun. 75:4891-4899, 2007). If facultative anaerobes efficiently lower oxygen availability in the intestine, then their sustained growth must also depend on anaerobic metabolism. In support of this idea, mutants lacking nitrate reductase or fumarate reductase have extreme colonization defects. Here, we further explore the role of anaerobic respiration in colonization using the streptomycin-treated mouse model. We found that respiratory electron flow is primarily via the naphthoquinones, which pass electrons to cytochrome bd oxidase and the anaerobic terminal reductases. We found that E. coli uses nitrate and fumarate in the intestine, but not nitrite, dimethyl sulfoxide, or trimethylamine N-oxide. Competitive colonizations revealed that cytochrome bd oxidase is more advantageous than nitrate reductase or fumarate reductase. Strains lacking nitrate reductase outcompeted fumarate reductase mutants once the nitrate concentration in cecal mucus reached submillimolar levels, indicating that fumarate is the more important anaerobic electron acceptor in the intestine because nitrate is limiting. Since nitrate is highest in the absence of E. coli, we conclude that E. coli is the only bacterium in the streptomycin-treated mouse large intestine that respires nitrate. Lastly, we demonstrated that a mutant lacking the NarXL regulator (activator of the NarG system), but not a mutant lacking the NarP-NarQ regulator, has a colonization defect, consistent with the advantage provided by NarG. The emerging picture is one in which gene regulation is tuned to balance expression of the terminal reductases that E. coli uses to maximize its competitiveness and achieve the highest possible population in the intestine.

Jones, Shari A.; Gibson, Terri; Maltby, Rosalie C.; Chowdhury, Fatema Z.; Stewart, Valley; Cohen, Paul S.; Conway, Tyrrell

2011-01-01

409

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

410

CELL WALL COMPOSITION AND VIRULENCE IN ESCHERICHIA COLI  

PubMed Central

Uridine diphosphate galactose 4-epimerase and phosphomannose isomerase-deficient mutants of Escherichia coli O111:B4 were studied to test the hypothesis that in E. coli a specific relationship exists between O antigenicity, virulence, and capacity to resist phagocytosis. The first mutant, designated J-5, produces a cell wall lipopolysaccharide, the side chains of which do not contain galactose, glucose, N-acetylglucosamine, or colitose. The second mutant produces a cell wall lipopolysaccharide which lacks only colitose. The capacity of these various organisms to kill mice was strikingly different. E. coli O111 was 1000 times as virulent as J-5, and 100 times as virulent as L-2. The capacity of the organisms to kill mice was correlated with their ability to resist phagocytosis and to persist in the peritoneal cavity. The parent strain of O111 resisted phagocytosis by macrophages in vivo and polymorphonuclear leukocytes in vitro. The mutants did not, and the organism most deficient in the saccharide component of its LPS was most susceptible to phagocytosis and least virulent. These results were corroborated by growing the mutants in appropriately supplemented media which permitted the synthesis of complete LPS, reversed the susceptibility to phagocytosis, and restored virulence. Finally, serological reactivity was consistent with previous observations which had demonstrated that the O antigenicity of E. coli is determined by the saccharide composition of its cell wall lipopolysaccharide. Despite the difference in the capacity of the various log-phase organisms to kill mice when injected intraperitoneally, purified lipopolysaccharides extracted from them did not differ significantly in their capacity to kill or produce fever. Thus virulence was shown to be independent of endotoxin activity which in turn seemed to be unrelated to the saccharide composition of the cell wall LPS. Collectively, these data provide at least a partial molecular definition of virulence in E. coli by demonstrating that the presence or absence of specific sugars in its cell wall lipopolysaccharide is a determinant of its antiphagocytic capacity and its virulence.

Medearis, Donald N.; Camitta, Bruce M.; Heath, Edward C.

1968-01-01

411

Profiling of the reactive oxygen species-related ecotoxicity of CuO, ZnO, TiO 2 , silver and fullerene nanoparticles using a set of recombinant luminescent Escherichia coli strains: differentiating the impact of particles and solubilised metals  

Microsoft Academic Search

We propose a novel combination of high-throughput luminescent bacterial tests for the evaluation of the reactive oxygen species\\u000a (ROS)-generating potential of engineered nanoparticles (eNPs) and the role of solubilised metal ions in this process. The\\u000a set of tests consists of differently engineered recombinant Escherichia coli strains: (1) a new sensor strain, which bioluminescence is induced by superoxide anions; (2) six

A. Ivask; O. Bondarenko; N. Jepihhina; A. Kahru

2010-01-01

412

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

413

Genotypic and Phenotypic Diversity among Induced, stx2Carrying Bacteriophages from Environmental Escherichia coli Strains  

Microsoft Academic Search

Shiga toxin 2 (stx2) gene-carrying bacteriophages have been shown to convert Escherichia coli strains to Shiga toxin-producing Escherichia coli (STEC). In this study, 79 E. coli strains belonging to 35 serotypes isolated from wastewaters of both human and animal origin were examined for the presence of stx2-carrying bacteriophages in their genomes. The lytic cycle of the bacteriophages was induced by

C. Garcia-Aljaro; Maite Muniesa; Juan Jofre; Anicet R. Blanch

2009-01-01

414

Across Genus Plasmid Transformation Between Bacillus subtilis and Escherichia coli and the Effect of Escherichia coli on the Transforming Ability of Free Plasmid DNA  

Microsoft Academic Search

The results presented in this article show that direct plasmid transfer from Escherichia coli carrying shuttle plasmid to Bacillus subtilis occurred when close contact between the two species was established by mixing E. coli and B. subtilis onto selective agar plates. The data demonstrate that the production of resistant colonies by plasmid transformation through\\u000a cell contact was DNase I sensitive

Xiaojuan Wang; Meiju Li; Qing Yan; Xiangdong Chen; Jing Geng; Zhixiong Xie; Ping Shen

2007-01-01

415

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

416

DNA polymerase switching: effects on spontaneous mutagenesis in Escherichia coli  

PubMed Central

Escherichia coli possesses five known DNA polymerases (pols). Pol III holoenzyme is the cell's main replicase, while pol I is responsible for the maturation of Okazaki fragments and filling gaps generated during nucleotide excision repair. Pols II, IV and V are significantly upregulated as part of the cell's global SOS response to DNA damage and under these conditions, may alter the fidelity of DNA replication by potentially interfering with the ability of pols I and III to complete their cellular functions. To test this hypothesis, we determined the spectrum of rpoB mutations arising in an isogenic set of mutL strains differentially expressing the chromosomally encoded pols. Interestingly, mutagenic hot spots in rpoB were identified that are susceptible to the actions of pols I–V. For example, in a recA730 lexA(Def) mutL background most transversions were dependent upon pols IV and V. In contrast, transitions were largely dependent upon pol I and to a lesser extent, pol III. Furthermore, the extent of pol I-dependent mutagenesis at one particular site was modulated by pols II and IV. Our observations suggest that there is considerable interplay among all five E. coli polymerases that either reduces or enhances the mutagenic load on the E. coli chromosome.

Curti, Elena; McDonald, John P; Mead, Samantha; Woodgate, Roger

2009-01-01

417

Discrepancies in the Enumeration of Escherichia coli1  

PubMed Central

Stationary-phase cells of Escherichia coli were enumerated by the pour plate method on Trypticase soy agar containing 0.3% yeast extract (TSYA), violet red-bile agar, and desoxycholate-lactose agar, and by the most-probable-number method in Brilliant Green-bile broth and lauryl sulfate broth. Maximum counts were assumed to be those on TSYA. In general, numbers detected were lower with the selective solid media and higher with the selective liquid media. Inhibitory effects, especially on selective solid media varied with the strains of E. coli. The lower detection on selective solid media was partly due to the stress induced in some cells by the temperature of the melted media used in the pour plate method. These cells apparently failed to repair and form colonies in the selective media. Improved detection on the selective solid media was achieved by using 1% nonfat milk solids, 1% peptone, or 1% MgSO4.7H2O in the dilution blanks. Higher detection on selective agar media was effected by surface plating or by surface-overlay plating of the cells. The surface-overlay method appeared to be superior for the direct enumeration of E. coli in foods.

Ray, B.; Speck, M. L.

1973-01-01

418

Reductive transformation of TNT by Escherichia coli: pathway description.  

PubMed

The reductive transformation of 2,4,6-trinitrotoluene (TNT) was studied using aerobically grown Escherichia coli cultures. In the absence of an external carbon or energy source, E. coli resting cells transformed TNT to hydroxylaminodinitrotoluenes (2HADNT, 4HADNT, with 4HADNT as the dominant isomer), aminodinitrotoluenes (4ADNT, with sporadic detection of 2ADNT), 2,4-di(hydroxylamino)-6-nitrotoluene (24D(HA)6NT), 2,4-diamino-6-nitrotoluene (24DA6NT), and an additional compound which was tentatively identified as a (hydroxylamino)aminonitrotoluene isomer via gas chromatography/mass spectroscopy and spectral analysis. The resting cell assay, performed in an oxygen-free atmosphere, avoided formation of azoxy dimers and provided good mass balances. Significant preference for reduction in the para versus ortho position was detected. The formation of 24D(HA)6NT, but not ADNT, appeared inhibited by the presence of TNT. The rate and extent of TNT reduction were significantly enhanced at higher cell densities, or by supplying an exogenous reducing power source, revealing the importance of enzyme concentration and reducing power. Whether the oxygen-insensitive E. coli nitroreductases, encoded by nfsA and nfsB, directly catalyze the TNT reduction or account for the complete TNT transformation pathway, remains to be determined. PMID:15490158

Yin, Hong; Wood, Thomas K; Smets, Barth F

2004-10-13

419

Recombinant expression of bioactive peptide lunasin in Escherichia coli.  

PubMed

Lunasin, a cancer-preventive peptide, was isolated from soybean, barley, and wheat. Previous studies showed that this 43-amino acid peptide has the ability to suppress chemical carcinogen-induced transformation in mammalian cells and skin carcinogenesis in mice. In this study, we attempted to use the Escherichia coli T7 expression system for expression of lunasin. The lunasin gene was synthesized by overlapping extension polymerase chain reaction and expressed in E. coli BL21(DE3) with the use of vector pET29a. The recombinant lunasin containing his-tag at the C-terminus was expressed in soluble form which could be purified by immobilized metal affinity chromatography. After 4 h, the expression level is above 4.73 mg of recombinant his-tagged lunasin/L of Luria-Bertani broth. It does not affect the bacterial growth and expression levels. This is the first study that successfully uses E. coli as a host to produce valuable bioactive lunasin. The result of in vitro bioassay showed that the purified recombinant lunasin can inhibit histone acetylation. Recombinant lunasin also inhibits the release of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, and nitric oxide production). Compared with other research methods on extraction or chemical synthesis to produce lunasin, our method is very efficient in saving time and cost. In the future, it could be applied in medicine and structure-function determination. PMID:20625716

Liu, Chin-Feng; Pan, Tzu-Ming

2010-07-13

420

Tetracycline Resistance in Escherichia coli Isolates from Hospital Patients  

PubMed Central

Hospital isolates of Escherichia coli resistant to tetracycline (TC) were studied to identify mechanisms which regulate TC resistance levels and ability to transfer TC resistance. Antibiotic resistance patterns, resistance levels to TC, and ability to transfer TC resistance were determined for the isolates. Similar data were obtained for the transferable plasmids after transfer to several new host strains of E. coli. Of the 110 isolates, 50% were able to transfer TC resistance by conjugation. There was a nearly linear relationship between the minimum inhibitory concentration (MIC) of TC for the hospital strains and the percentage of strains at a given MIC that could transfer TC resistance. The strains that were simultaneously resistant to tetracycline, streptomycin, and ampicillin had relatively high MICs of TC and high ability to transfer TC resistance. These results and surveys of TC-resistant E. coli by others suggest that TC resistance levels and transmissibility may be influenced by other resistance markers. The isolates which did not transfer TC resistance by conjugation were tested for the presence of TC resistance plasmids by mobilization or by transformation with deoxyribonucleic acid from the isolates. Evidence for plasmid-mediated TC resistance was found in 92 (84%) of the 110 hospital strains.

Camiolo, S. M.; Beck, M. E.; Reynard, A. M.

1975-01-01

421

Active efflux of bile salts by Escherichia coli.  

PubMed Central

Enteric bacteria such as Escherichia coli must tolerate high levels of bile salts, powerful detergents that disrupt biological membranes. The outer membrane barrier of gram-negative bacteria plays an important role in this resistance, but ultimately it can only retard the influx of bile salts. We therefore examined whether E. coli possessed an energy-dependent efflux mechanism for these compounds. Intact cells of E. coli K-12 appeared to pump out chenodeoxycholate, since its intracellular accumulation increased more than twofold upon deenergization of the cytoplasmic membrane by a proton conductor. Growth inhibition by bile salts and accumulation levels of chenodeoxycholate increased when mutations inactivating the acrAB and emrAB gene clusters were introduced. The AcrAB system especially appeared to play a significant role in bile acid efflux. However, another efflux system(s) also plays an important role, since the accumulation level of chenodeoxycholate increased strongly upon deenergization of acrA emrB double mutant cells. Everted membrane vesicles accumulated taurocholate in an energy-dependent manner, apparently consuming delta pH without affecting delta psi. The efflux thus appears to be catalyzed by a proton antiporter. Accumulation by the everted membrane vesicles was not decreased by mutations in acr and emrB genes and presumably reflects activity of the unknown system seen in intact cells. It followed saturation kinetics with Vmax and Km values in the neighborhood of 0.3 nmol min(-1) mg of protein(-1) and 50 microM, respectively.

Thanassi, D G; Cheng, L W; Nikaido, H

1997-01-01

422

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

423

Host species-specific translocation of Escherichia coli.  

PubMed

The purpose of this paper is to investigate the rate of translocation of Escherichia coli strains in different experimental/animal models. Four proficient translocating E. coli strains isolated from mesenteric lymph nodes (MLNs) and/or the blood of rats (strains KIC-1 and KIC-2), from a fatal case of pancreatitis (HMLN-1) and from pigs (PC-1 isolated in this study) were tested for their ability to translocate across two host species and the Caco-2 cell line as a model of the human gut epithelium. HMLN-1 was found in the MLNs of all 15 pigs tested. This strain, however, did not translocate in any rats and only colonised the caecum of four rats in small numbers. HMLN-1 and PC-1 were the dominant translocating strains in Caco-2 cells compared to KIC-1 and KIC-2, which were found to translocate at a lower rate in pigs and in Caco-2 cells. The rate of translocation of PC-1 in rats was also very low compared to KIC-1 and KIC-2. We suggest that, in studies aiming to investigate the mechanism of translocation of E. coli strains isolated from humans, rats may not be an appropriate animal model and that the Caco-2 cells or pigs are more suitable in vitro and in vivo models, respectively. PMID:19437050

Katouli, M; Ramos, N L; Nettelbladt, C G; Ljungdahl, M; Robinson, W; Ison, H M; Brauner, A; Möllby, R

2009-05-13

424

Colicin translocation across the Escherichia coli outer membrane.  

PubMed

We are investigating how protein bacteriocins import their toxic payload across the Gram-negative cell envelope, both as a means of understanding the translocation process itself and as a means of probing the organization of the cell envelope and the function of the protein machines within it. Our work focuses on the import mechanism of the group A endonuclease (DNase) colicin ColE9 into Escherichia coli, where we combine in vivo observations with structural, biochemical and biophysical approaches to dissect the molecular mechanism of colicin entry. ColE9 assembles a multiprotein 'translocon' complex at the E. coli outer membrane that triggers entry of the toxin across the outer membrane and the simultaneous jettisoning of its tightly bound immunity protein, Im9, in a step that is dependent on the protonmotive force. In the present paper, we focus on recent work where we have uncovered how ColE9 assembles its translocon complex, including isolation of the complex, and how this leads to subversion of a signal intrinsic to the Tol-Pal assembly within the periplasm and inner membrane. In this way, the externally located ColE9 is able to 'connect' to the inner membrane protonmotive force via a network of protein-protein interactions that spans the entirety of the E. coli cell envelope to drive dissociation of Im9 and initiate entry of the colicin into the cell. PMID:23176501

Housden, Nicholas G; Kleanthous, Colin

2012-12-01

425

Improved phloroglucinol production by metabolically engineered Escherichia coli.  

PubMed

Phloroglucinol is a valuable chemical which has been successfully produced by metabolically engineered Escherichia coli. However, the low productivity remains a bottleneck for large-scale application and cost-effective production. In the present work, we cloned the key biosynthetic gene, phlD (a type III polyketide synthase), into a bacterial expression vector to produce phloroglucinol in E. coli and developed different strategies to re-engineer the recombinant strain for robust synthesis of phloroglucinol. Overexpression of E. coli marA (multiple antibiotic resistance) gene enhanced phloroglucinol resistance and elevated phloroglucinol production to 0.27 g/g dry cell weight. Augmentation of the intracellular malonyl coenzyme A (malonyl-CoA) level through coordinated expression of four acetyl-CoA carboxylase (ACCase) subunits increased phloroglucinol production to around 0.27 g/g dry cell weight. Furthermore, the coexpression of ACCase and marA caused another marked improvement in phloroglucinol production 0.45 g/g dry cell weight, that is, 3.3-fold to the original strain. Under fed-batch conditions, this finally engineered strain accumulated phloroglucinol up to 3.8 g/L in the culture 12 h after induction, corresponding to a volumetric productivity of 0.32 g/L/h. This result was the highest phloroglucinol production to date and showed promising to make the bioprocess economically feasible. PMID:21643705

Cao, Yujin; Jiang, Xinglin; Zhang, Rubing; Xian, Mo

2011-06-04

426

Assembly proteins of CS1 pili of enterotoxigenic Escherichia coli.  

PubMed

Some strains of enterotoxigenic Escherichia coli associated with human diarrhoeal disease produce a class of pili represented by those called CS1. For the assembly of the major-pilin subunit, CooA, into pili, each of four linked genes, cooB, A, C, and D, is required. In this study, we have determined the subcellular localization of CooB, C and D, and investigated the molecular interactions of these proteins using specific antisera. CooD appears to be an integral pilus protein because it co-purifies with, and is strongly associated with, CS1 pili. In keeping with its role as an assembly protein, the CooD minor pilin (when overexpressed in CS1-piliated strains) was detected in periplasmic intermolecular complexes with the major-pilin subunit CooA. CooB is an assembly protein found exclusively in the periplasm of CS1-piliated strains. CooB also forms periplasmic intermolecular complexes with CooA, but does not constitute part of the final pilus structure. Immunoblot analysis of cell fractions showed that CooC is an outer membrane protein of CS1-piliated E. coli. Based on this information, we have proposed a model for CS1-pilus assembly which is very similar to the model for polymerization of the PapA pilin of uropathogenic E. coli. As the assembly proteins of Pap and CS1 pili are structurally unrelated, this may represent a case of convergent evolution. PMID:8866477

Sakellaris, H; Balding, D P; Scott, J R

1996-08-01

427

Transcription mapping of the Escherichia coli chromosome by electron microscopy.  

PubMed Central

The distinctive double Christmas tree morphology of rRNA operons as visualized by electron microscopy makes them easy to recognize in chromatin spreads from Escherichia coli. On the basis of the pattern of nascent transcripts on nearby transcription units and the relative distances of the operons from one another and the replication origin, we are now able to specifically identify five of the seven rRNA operons in E. coli. The use of rRNA operons as markers of both position and distance has resulted in the morphological mapping of a significant portion of the E. coli chromosome; over 600 kilobase pairs in the 84- to 90-min and 72-min regions can now be recognized. Since individual rRNA operons could be identified, direct comparisons could be made of their transcriptional activities. As judged by the densities of RNA polymerases along the operons, rrnA, rrnB, rrnC, rrnD, and rrnE were all transcribed at similar levels, with one RNA polymerase every 85 base pairs. The ability to recognize individual operons and specific regions of the chromosome allows direct comparisons of various genetic parameters. Images

French, S L; Miller, O L

1989-01-01

428

Studies on the endogenous metabolism of Escherichia coli  

PubMed Central

1. The endogenous metabolism of Escherichia coli has been studied by examining changes in cellular composition and of the suspending fluid during starvation of washed suspensions of the organism, in water or in phosphate buffer, at 37° under aerobic and anaerobic conditions. 2. When E. coli is grown in glucose–ammonium salts media the cells contain glycogen, which is utilized rapidly during subsequent starvation of the cells. 3. Ammonia is released by starved cells only after a lag period, which corresponds to the time taken for the cellular glycogen to be almost completely utilized. 4. If cells are grown under conditions that permit incorporation of 14C into protein but not into glycogen and are then starved, release of 14CO2 commences immediately and continues at a linear rate throughout the period of glycogen utilization; it is concluded that the presence of glycogen in the cell prevents the net degradation of nitrogenous materials but does not suppress protein turnover. 5. RNA is degraded by the cells immediately they are starved, ribose is oxidized and ultraviolet-absorbing materials are released to the suspending medium. 6. There is no significant utilization of lipid during the starvation of glucose-grown E. coli. 7. There is no loss of viability during the initial 12hr. period of starvation under either aerobic or anaerobic conditions, but thereafter the cells die more rapidly under conditions of anaerobiosis. 8. These results are discussed in relation to the known patterns of endogenous metabolism and survival of other bacteria.

Dawes, E. A.; Ribbons, D. W.

1965-01-01

429

Adenosine diphosphate sugar pyrophosphatase prevents glycogen biosynthesis in Escherichia coli  

PubMed Central

An adenosine diphosphate sugar pyrophosphatase (ASPPase, EC 3.6.1.21) has been characterized by using Escherichia coli. This enzyme, whose activities in the cell are inversely correlated with the intracellular glycogen content and the glucose concentration in the culture medium, hydrolyzes ADP-glucose, the precursor molecule of glycogen biosynthesis. ASPPase was purified to apparent homogeneity (over 3,000-fold), and sequence analyses revealed that it is a member of the ubiquitously distributed group of nucleotide pyrophosphatases designated as “nudix” hydrolases. Insertional mutagenesis experiments leading to the inactivation of the ASPPase encoding gene, aspP, produced cells with marginally low enzymatic activities and higher glycogen content than wild-type bacteria. aspP was cloned into an expression vector and introduced into E. coli. Transformed cells were shown to contain a dramatically reduced amount of glycogen, as compared with the untransformed bacteria. No pleiotropic changes in the bacterial growth occurred in both the aspP-overexpressing and aspP-deficient strains. The overall results pinpoint the reaction catalyzed by ASPPase as a potential step of regulating glycogen biosynthesis in E. coli.

Moreno-Bruna, Beatriz; Baroja-Fernandez, Edurne; Munoz, Francisco Jose; Bastarrica-Berasategui, Ainara; Zandueta-Criado, Aitor; Rodriguez-Lopez, Milagros; Lasa, Inigo; Akazawa, Takashi; Pozueta-Romero, Javier

2001-01-01

430

Evidence for clonal population structure in Escherichia coli.  

PubMed Central

Genotypes of 142 K1 isolates of four O serogroups of Escherichia coli from human hosts in Europe and the United States were characterized by an electrophoretic analysis of allozymic variation in 12 chromosomally encoded enzymes. The genetic structure of natural populations revealed by this analysis is closely similar to that indicated in earlier studies by Achtman and colleagues of the electrophoretic migration pattern for four outer membrane proteins and the chemical structure of the cell-wall lipopolysaccharides. The combined evidence demonstrates that most of the K1 isolates belong to a small number of geographically widespread clones. The distribution of O serogroups among the isolates does not consistently correspond to the clonal structure; O1:K1 isolates represent at least two distantly related, geographically widespread clones, one of which is genetically similar to a clone of the O18:K1 serotype. These findings for K1 isolates add to a growing body of evidence supporting the hypothesis that the genetic structure of natural populations of E. coli is basically clonal, with very limited recombination of chromosomal genes. Clonal structure has important implications for the study of the determinants of pathogenicity and disease specificity in E. coli.

Ochman, H; Selander, R K

1984-01-01

431

Metabolomic and transcriptomic stress response of Escherichia coli  

PubMed Central

Environmental fluctuations lead to a rapid adjustment of the physiology of Escherichia coli, necessitating changes on every level of the underlying cellular and molecular network. Thus far, the majority of global analyses of E. coli stress responses have been limited to just one level, gene expression. Here, we incorporate the metabolite composition together with gene expression data to provide a more comprehensive insight on system level stress adjustments by describing detailed time-resolved E. coli response to five different perturbations (cold, heat, oxidative stress, lactose diauxie, and stationary phase). The metabolite response is more specific as compared with the general response observed on the transcript level and is reflected by much higher specificity during the early stress adaptation phase and when comparing the stationary phase response to other perturbations. Despite these differences, the response on both levels still follows the same dynamics and general strategy of energy conservation as reflected by rapid decrease of central carbon metabolism intermediates coinciding with downregulation of genes related to cell growth. Application of co-clustering and canonical correlation analysis on combined metabolite and transcript data identified a number of significant condition-dependent associations between metabolites and transcripts. The results confirm and extend existing models about co-regulation between gene expression and metabolites demonstrating the power of integrated systems oriented analysis.

Jozefczuk, Szymon; Klie, Sebastian; Catchpole, Gareth; Szymanski, Jedrzej; Cuadros-Inostroza, Alvaro; Steinhauser, Dirk; Selbig, Joachim; Willmitzer, Lothar

2010-01-01

432

Binding characteristics of Escherichia coli adhesins in human urinary bladder.  

PubMed Central

We studied domains in the human bladder that acted as receptors for Escherichia coli P, S, type 1, type 1C, and O75X fimbriae or adhesin and domains in the human kidneys that were receptors for E. coli type 1C fimbriae. Binding sites in frozen tissue sections were localized by direct staining with fluorochrome-labeled recombinant strains and by indirect immunofluorescence with the purified adhesins. In the bladder, the P and S fimbriae showed closely similar binding to the epithelial and muscular layers, and the S fimbriae also bound to the connective tissue elements. Type 1 fimbriae bound to vascular walls and to muscle cells, whereas the O75X adhesin bound avidly to connective tissue elements and to some extent to epithelial and muscle cells of the bladder. The type 1C fimbriae bound to distal tubules and collecting ducts of the kidney and to vascular endothelial cells in both the kidney and bladder. The binding of all adhesin types was inhibited by specific receptor analogs or Fab fragments. The results reveal a possible mechanism by which the type 1C fimbriae may help invasion of E. coli in the kidneys but do not support a pathogenetic role for type 1 fimbriae. Similar tissue specificity of P and S fimbriae in the human urinary tract indicates that the presence of binding sites on uroepithelia does not fully explain the virulence properties of P fimbriae in human urinary tract infections. Images

Virkola, R; Westerlund, B; Holthofer, H; Parkkinen, J; Kekomaki, M; Korhonen, T K

1988-01-01

433

Efficacy of cefmenoxime in experimental Escherichia coli bacteremia and meningitis.  

PubMed Central

Cefmenoxime, a new semisynthetic cephalosporin structurally similar to cefotaxime, was evaluated for its activities in vitro and in vivo against a K1 Escherichia coli strain in comparison with activities of cefotaxime and ampicillin. In vitro the MICs and MBCs of both cefmenoxime and cefotaxime were the same, 1/16th and 1/32nd those of ampicillin, respectively. The efficacies of cefmenoxime and cefotaxime against experimentally induced E. coli bacteremia and meningitis in newborn rats were similar and significantly better than that of ampicillin as judged by bactericidal titers of blood and cerebrospinal fluid, rapidity of clearance of bacteria from blood and cerebrospinal fluid, and incidence of meningitis in animals with bacteremias. The efficacy of cefmenoxime or cefotaxime measured by impact on mortality was influenced by the size of bacterial populations. The mortality was significantly greater in rats with bacterial counts before therapy of greater than or equal to 10(6) CFU/ml of blood than in animals with lower counts. Overall, the in vivo efficacy of cefmenoxime was similar to that of cefotaxime; thus it could be useful in the therapy of neonatal E. coli infection.

Kim, K S

1985-01-01

434

Instability of Pathogenicity Islands in Uropathogenic Escherichia coli 536  

PubMed Central

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

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

2004-01-01

435

Mechanisms of acid resistance in enterohemorrhagic Escherichia coli.  

PubMed Central

Enterohemorrhagic strains of Escherichia coli must pass through the acidic gastric barrier to cause gastrointestinal disease. Taking into account the apparent low infectious dose of enterohemorrhagic E. coli, 11 O157:H7 strains and 4 commensal strains of E. coli were tested for their abilities to survive extreme acid exposures (pH 3). Three previously characterized acid resistance systems were tested. These included an acid-induced oxidative system, an acid-induced arginine-dependent system, and a glutamate-dependent system. When challenged at pH 2.0, the arginine-dependent system provided more protection in the EHEC strains than in commensal strains. However, the glutamate-dependent system provided better protection than the arginine system and appeared equally effective in all strains. Because E. coli must also endure acid stress imposed by the presence of weak acids in intestinal contents at a pH less acidic than that of the stomach, the ability of specific acid resistance systems to protect against weak acids was examined. The arginine- and glutamate-dependent systems were both effective in protecting E. coli against the bactericidal effects of a variety of weak acids. The acids tested include benzoic acid (20 mM; pH 4.0) and a volatile fatty acid cocktail composed of acetic, propionic, and butyric acids at levels approximating those present in the intestine. The oxidative system was much less effective. Several genetic aspects of E. coli acid resistance were also characterized. The alternate sigma factor RpoS was shown to be required for oxidative acid resistance but was only partially involved with the arginine- and glutamate-dependent acid resistance systems. The arginine decarboxylase system (including adi and its regulators cysB and adiY) was responsible for arginine-dependent acid resistance. The results suggest that several acid resistance systems potentially contribute to the survival of pathogenic E. coli in the different acid stress environments of the stomach (pH 1 to 3) and the intestine (pH 4.5 to 7 with high concentrations of volatile fatty acids). Of particular importance to the food industry was the finding that once induced, the acid resistance systems will remain active for prolonged periods of cold storage at 4 degrees C.

Lin, J; Smith, M P; Chapin, K C; Baik, H S; Bennett, G N; Foster, J W

1996-01-01

436

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...

437

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

438

DISCRIMINTION OF ESCHERICHIA COLI O157:H7 ISOLATES BY GENOTYPING SINGLE NUCLEOTIDE POLYMORPHISMS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli O157:H7 is the major cause of hemorrhagic colitis and hemolytic uremic syndrome in the United States. The locus of enterocyte effacement (LEE) is one of the pathogenicity islands of E. coli O157:H7 which encodes for genes involved in the adherence of E. coli O157:H7 to intestinal e...

439

Cow milk yield and composition before development of Escherichia coli mastitis  

Microsoft Academic Search

High milk yield, low milk fat and low milk protein were considered as possible predisposing factors to bovine Escherichia coli mastitis. Morning and afternoon milk yields were recorded in 46 Friesian cows later developing E coli mastitis and compared with 92 uninfected controls. Animals developing E coli mastitis gave a significantly higher milk yield than controls. The overall morning: afternoon

TO Jones; PC Jones

1986-01-01

440

Extraintestinal Escherichia coli isolations from SIDS cases and other cases of sudden death in Victoria, Australia  

Microsoft Academic Search

This investigation is an extension of previous studies on the possible role of intestinal Escherichia coli in sudden infant death syndrome (SIDS) to include the isolation of extraintestinal E. coli. The lungs of 52 and the blood of 144 SIDS infants were cultured and isolates were investigated. E. coli was isolated from about a quarter of post-mortem lung samples and

Jane L Pearce; Richard K. J Luke; Karl A Bettelheim

1999-01-01

441

Identification of Fecal Escherichia coli from Humans and Animals by Ribotyping  

Microsoft Academic Search

Fecal pollution of water resources is an environmental problem of increasing importance. Identification of individual host sources of fecal Escherichia coli, such as humans, pets, production animals, and wild animals, is prerequisite to formulation of remediation plans. Ribotyping has been used to distinguish fecal E. coli of human origin from pooled fecal E. coli isolates of nonhuman origin. We have

C. ANDREW CARSON; BRIAN L. SHEAR; MARK R. ELLERSIECK; AMHA ASFAW

2001-01-01

442

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

443

Comparison of commercially available Escherichia coli enumeration tests: Implications for attaining water quality standards  

Microsoft Academic Search

Many states are replacing microbiological water quality standards based on “fecal” or thermotolerant coliforms (ThCs) with new standards that employ Escherichia coli as the indicator organism. Implicit in these new standards are assumptions about the equivalence of E. coli enumeration tests and the E. coli levels that will provide protection equivalent to former ThC standards. To investigate these assumptions, E.

William P. Hamilton; Moonil Kim; Edward L. Thackston

2005-01-01

444

Genome sequence of Escherichia coli J53, a reference strain for genetic studies.  

PubMed

Escherichia coli J53 (F(-) met pro Azi(r)) is a derivative of E. coli K-12 which is resistant to sodium azide. This strain has been widely used as a general recipient strain for various conjugation experiments. Here, we report the genome sequence of E. coli J53 (=KACC 16628). PMID:22740669

Yi, Hana; Cho, Yong-Joon; Yong, Dongeun; Chun, Jongsik

2012-07-01

445

Genome Sequence of Escherichia coli J53, a Reference Strain for Genetic Studies  

PubMed Central

Escherichia coli J53 (F? met pro Azir) is a derivative of E. coli K-12 which is resistant to sodium azide. This strain has been widely used as a general recipient strain for various conjugation experiments. Here, we report the genome sequence of E. coli J53 (=KACC 16628).

Yi, Hana; Cho, Yong-Joon; Yong, Dongeun

2012-01-01

446

Genotypic diversity of escherichia coli isolates from environmental sources and the influence on transport behavior  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli (E. coli) is a dominant intestinal commensal organism, an important fecal indicator bacterium (FIB), a pathogen and a target for microbial source tracking (MST). Strain level differences (genotypic and phenotypic) in E. coli influence its fate and transport and therefore have import...

447

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

ERIC Educational Resources Information Center

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

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

2004-01-01

448

Escherichia coli detection by GFP-labeled lysozyme-inactivated T4 bacteriophage  

Microsoft Academic Search

Escherichia coli has been used as an indicator of the fecal contamination of water and food, identifying potential health hazards. In this study, an E. coli-specific bacteriophage, T4, was used to detect E. coli bacteria. The T4 phage small outer capsid (SOC) protein was used to present green fluorescent protein (GFP), an easily detectable marker protein, on the phage capsid.

Yasunori Tanji; Chiaki Furukawa; Suk-Hyun Na; Tomonori Hijikata; Kazuhiko Miyanaga; Hajime Unno

2004-01-01

449

Synchronized disruption of Escherichia coli cells by T4 phage infection  

Microsoft Academic Search

For development of an autolytic Escherichia coli protein expression system, T4 bacteriophage (T4)-mediated E. coli disruption was investigated. At least two types of E. coli cell lysis, “lysis from without” (LO) and “lysis from within” (LI), are known to be induced by T4. The efficiency of cell disruption was monitored by the release of ?-galactosidase from the cells. In the

Kazuhiro Asami; Xin-Hui Xing; Yasunori Tanji; Hajime Unno

1997-01-01

450

Genetic Characterization of Escherichia coli O104 Isolates from Different Sources in the United States  

PubMed Central

Escherichia coli O104 isolates collected from different sources in the United States were examined for virulence genes typical of enterohemorrhagic E. coli and those identified in the O104:H4 isolate associated with the 2011 German outbreak. The unexpected presence of virulence markers in these isolates highlights the importance of screening unusual and potentially pathogenic Shiga toxin-producing E. coli serotypes.

Rump, Lydia V.; Bodeis-Jones, Sonya; Abbott, Jason; Zhao, Shaohua; Kase, Julie; Lorenz, Sandra; Fischer, Markus; Brown, Eric

2012-01-01

451

Escherichia coli O157:H7 in drinking water from private water supplies in the Netherlands  

Microsoft Academic Search

The microbiological quality of drinking water from 144 private water supplies in the Netherlands was tested and additionally the occurrence of Escherichia coli O157 was examined. Faecal indicators were enumerated by using standard membrane filtration methods. The presence of E. coli O157 was determined using a specific enrichment method. Eleven percent of the samples contained faecal indicators whereas E. coli

Franciska M. Schets; Ronald Italiaander; Leo Heijnen; Saskia A. Rutjes; Willem K. van der Zwaluw; Ana Maria de Roda Husman

2005-01-01

452

The Regulation of Colicin Synthesis and Colicin Factor Transfer in Escherichia coli K 12  

Microsoft Academic Search

SUMMARY Cells of Escherichia coli, newly infected with the colicin I factor (colI), showed an enhanced efficiency of transfer of this factor (HFC), and were also more likely to undergo lethal colicin synthesis, than were stably colicinogenic cells. Up to 20% of the cells of stably colI+ strains were induced to produce colicin by ultraviolet irradiation, and from such irradiated

MARILYN MONK; R. C. Clowes

1964-01-01

453

Antibiotic resistance indexing of Escherichia coli to identify sources of fecal contamination in water.  

PubMed

A total of 202 Escherichia coli isolated from urban and rural water were tested with 11 antibiotics to assess the prevalence of antibiotic resistance from each source. Urban waters harbored higher percentages of resistant E. coli strains than rural waters. Antibiotic-resistant E. coli may offer an index of water quality related to source. PMID:2081335

Kaspar, C W; Burgess, J L; Knight, I T; Colwell, R R

1990-12-01

454

Molecular characterization of diarrheagenic Escherichia coli strains from stools samples and food products in Colombia  

Microsoft Academic Search

The prevalence of diarrheagenic Escherichia coli in childhood diarrhea and the role of contaminated food products in disease transmission in Colombia are largely unknown. The aim of this study is to identify E. coli pathotypes, including E. coli O157:H7, from 108 stool samples from children with acute diarrhea, 38 meat samples and 38 vegetable samples. Multiplex PCR and Bax Dupont

Laura Cristina Rúgeles; Jing Bai; Aída Juliana Martínez; María Consuelo Vanegas; Oscar Gilberto Gómez-Duarte

2010-01-01

455

Diet, Escherichia coli 0157:H7, and cattle, a review after 10 years  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

456

Antibiotic resistance in Escherichia coli isolates obtained from animals, foods and humans in Spain  

Microsoft Academic Search

Antibiotic resistance was investigated in 474 Escherichia coli isolates recovered from animal faeces (broilers, pigs, pets, bulls and horses), human faeces (patients and healthy volunteers) and food products of animal origin. E. coli isolates (3260) recovered from human significant infectious samples were also included. There was a high frequency of nalidixic acid, ciprofloxacin and gentamicin resistance in E. coli isolates

Yolanda Sáenz; Myriam Zarazaga; Laura Briñas; Marta Lantero; Fernanda Ruiz-Larrea; Carmen Torres

2001-01-01

457

Determination of Plasmid DNA Concentration Maintained by Nonculturable 'Escherichia coli' in Marine Microcosms.  

National Technical Information Service (NTIS)

The concentration of plasmid pBR322 DNA in nonculturable Escherichia coli JM83 was measured to determine whether the plasmid concentration changed during survival of E. coli in marine and estuarine water. E. coli JM83 containing the plasmid pBR322 was pla...

J. J. Byrd J. G. Leahy R. R. Colwell

1992-01-01

458

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

459

Uropathogenic Escherichia coli are less likely than paired fecal E. coli to have CRISPR loci.  

PubMed

CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats) are short fragments of DNA that act as an adaptive immune system protecting bacteria against invasion by phages, plasmids or other forms of foreign DNA. Bacteria without a CRISPR locus may more readily adapt to environmental changes by acquiring foreign genetic material. Uropathogenic Escherichia coli (UPEC) live in a number of environments suggesting an ability to rapidly adapt to new environments. If UPEC are more adaptive than commensal E. coli we would expect that UPEC would have fewer CRISPR loci, and - if loci are present - that they would harbor fewer spacers than CRISPR loci in fecal E. coli. We tested this in vivo by comparing the number of CRISPR loci and spacers, and sensitivity to antibiotics (resistance is often obtained via plasmids) among 81 pairs of UPEC and fecal E. coli isolated from women with urinary tract infection. Each pair included one uropathogen and one commensal (fecal) sample from the same female patient. Fecal isolates had more repeats (p=0.009) and more unique spacers (p<0.0001) at four CRISPR loci than uropathogens. By contrast, uropathogens were more likely than fecal E. coli to be resistant to ampicillin, cefazolin and trimethoprim/sulfamethoxazole. However, no consistent association between CRISPRs and antibiotic resistance was identified. To our knowledge, this is the first study to compare fecal E. coli and pathogenic E. coli from the same individuals, and to test the association of CRISPR loci with antibiotic resistance. Our results suggest that the absence of CRISPR loci may make UPEC more susceptible to infection by phages or plasmids and allow them to adapt more quickly to various environments. PMID:23891665

Dang, Trang Nguyen Doan; Zhang, Lixin; Zöllner, Sebastian; Srinivasan, Usha; Abbas, Khadija; Marrs, Carl F; Foxman, Betsy

2013-07-25

460

A biosensor for the detection of gas toxicity using a recombinant bioluminescent bacterium  

Microsoft Academic Search

A whole-cell biosensor was developed for the detection of gas toxicity using a recombinant bioluminescent Escherichia coli harboring a lac::luxCDABE fusion. Immobilization of the cells within LB agar has been done to maintain the activity of the microorganisms and to detect the toxicity of chemicals through the direct contact with gas. Benzene, known as a representative volatile organic compound, was

Geun Cheol Gil; Robert J. Mitchell; Suk Tai Chang; Man Bock Gu

2000-01-01

461

Genetic analysis of Escherichia coli oligopeptide transport mutants.  

PubMed Central

The composition of the outer membrane channels formed by the OmpF and OmpC porins is important in peptide permeation, and elimination of these proteins from the Escherichia coli outer membrane results in a cell in which the primary means for peptide permeation through this cell structure has been lost. E. coli peptide transport mutants which harbor defects in genes other than the ompF/ompC genes have been isolated on the basis of their resistance to toxic tripeptides. The genetic defects carried by these oligopeptide permease-negative (Opp-) strains were found to map in two distinct chromosomal locations. One opp locus was trp linked and mapped to the interval between att phi 80 and galU. Complementation studies with F'123 opp derivatives indicated that this peptide transport locus resembles that characterized in Salmonella typhimurium as a tetracistronic operon (B. G. Hogarth and C. F. Higgins, J. Bacteriol. 153:1548-1551, 1983). The second opp locus, which we have designated oppE, was mapped to the interval between dnaC and hsd at 98.5 min on the E. coli chromosome. The differences in peptide utilization, sensitivity and resistance to toxic peptides, and the L-[U-14C]alanyl-L-alanyl-L-alanine transport properties observed with these Opp-E. coli strains demonstrated that the transport systems encoded by the trp-linked opp genes and by the oppE gene(s) have different substrate preferences. Mutants harboring defects in both peptide transport loci defined in this study would not grow on nutritional peptides except for tri-L-methionine, were totally resistant to toxic peptides, and would not actively transport L-[U-14C]alanyl-L-alanyl-L-alanine.

Andrews, J C; Short, S A

1985-01-01