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1

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

Microsoft Academic Search

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

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

2008-01-01

2

Multiplexed amino acid array utilizing bioluminescent Escherichia coli auxotrophs.  

PubMed

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

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

2010-05-15

3

In Vivo Imaging of Bioluminescent Escherichia coli in a Cutaneous Wound Infection Model for Evaluation of an Antibiotic Therapy  

Microsoft Academic Search

A rapid, continuous method for noninvasively monitoring the effectiveness of several antibacterial agents in real time by using a model of wound infection was developed. This study was divided into three steps: (i) construction of a plasmid to transform Escherichia coli into a bioluminescent variant, (ii) study of the bioluminescent E. coli in vitro as a function of temperature and

Samir Jawhara; Serge Mordon

2004-01-01

4

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. PMID:22164050

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

2011-01-01

5

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

6

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

Technology Transfer Automated Retrieval System (TEKTRAN)

Our objectives were to develop an ovine model for Escherichia coli-induced preterm delivery, and monitor E. coli (lux modified for photonic detection) invasion of the fetal environment—ewes (124 ± 18 d of gestation) received intrauterine inoculations using E. coli-lux as follows: control (n = 5), 1....

7

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. PMID:22716772

2012-01-01

8

LuxArray, a High-Density, Genomewide Transcription Analysis of Escherichia coli Using Bioluminescent Reporter Strains  

Microsoft Academic Search

A sequenced collection of plasmid-borne random fusions of Escherichia coli DNA to a Photorhabdus lumine- scens luxCDABE reporter was used as a starting point to select a set of 689 nonredundant functional gene fusions. This group, called LuxArray 1.0, represented 27% of the predicted transcriptional units in E. coli. High-density printing of the LuxArray 1.0 reporter strains to membranes on

TINA K. VAN DYK; ELLEN J. DEROSE; GREGORY E. GONYE

2001-01-01

9

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

10

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. PMID:9457432

Nataro, James P.; Kaper, James B.

1998-01-01

11

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...

12

Escherichia coli biofilms  

PubMed Central

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

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

2008-01-01

13

Article de synthse Escherichia coli  

E-print Network

Article de synthèse Escherichia coli entéropathogènes du lapin D Licois INRA, Station de pathologie diarrhée, chez l'homme ou l'animal. Escherichia coli/ entéropathogène / entérohémorragique / lapin Summary ― Enteropathogenic Escherichia coli from the rabbit. Intestinal pathology is the main cause

Paris-Sud XI, Université de

14

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

15

Bioluminescence  

NSDL National Science Digital Library

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

John W. Kimball

16

Review article Avian pathogenic Escherichia coli (APEC)  

E-print Network

Review article Avian pathogenic Escherichia coli (APEC) Maryvonne Dho-Moulina John Morris Inra/Elscvier, Paris. avian / Escherichia coli / virulence / fimbriae / capsule / aerobactin.int-a. li- #12;Résumé-Escherichia coli pathogènes aviaires (APEC). Les Escherichia coli pathogènes aviaires

Paris-Sud XI, Université de

17

Escherichia coli proteomics and bioinformatics  

E-print Network

ESCHERICHIA COLI PROTEOMICS AND BIOINFORMATICS A Dissertation by LILI NIU Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirement for the degree of DOCTOR OF PHILOSOPHY... May 2007 Major Subject: Biochemistry ESCHERICHIA COLI PROTEOMICS AND BIOINFORMATICS A Dissertation by LILI NIU Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements...

Niu, Lili

2009-05-15

18

Review article Enterotoxigenic Escherichia coli (ETEC)  

E-print Network

Review article Enterotoxigenic Escherichia coli (ETEC) in farm animals Béla Nagy* Péter Zs. Fekete to enterotoxigenic Escherichia coli (ETEC) typically appear as severe watery diarrhoea during the first few daysC novell.vnu-i.hu Résumé - Escherichia coli entérotoxigène (ETEC) chez les animaux de la ferme. L

Paris-Sud XI, Université de

19

ORIGINAL ARTICLE Competitive interactions in Escherichia coli  

E-print Network

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

Riley, Margaret

20

EXTRAINTESTINAL PATHOGENIC ESCHERICHIA COLI (EXPEC)  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

21

Physicochemical characterization of Escherichia coli  

Microsoft Academic Search

EightEscherichia coli strains were characterized by determining their adhesion to xylene, surface free energy, zeta potential, relative surface\\u000a charge, and their chemical composition. The latter was done by applying X-ray photoelectron spectroscopy (XPS) and infrared\\u000a spectroscopy (IR). No relationship between the adhesion to xylene and the water contact angles of these strains was found.\\u000a Three strains had significantly lower surface

G. Harkes; H. C. van der Mei; P. G. Rouxhet; J. Dankert; H. J. BrJSSCHER; J. Feijen

1992-01-01

22

ORIGINAL RESEARCH Shigella Strains Are Not Clones of Escherichia coli  

E-print Network

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

Hao, Bailin

23

The Escherichia coli Peripheral Inner Membrane Proteome*S  

E-print Network

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

Economou, Tassos

24

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...

25

Improvement of Escherichia coli growth by kaolinite  

Microsoft Academic Search

Knowledge of the impacts of clay minerals on microorganisms is essential to a complete understanding of microbially-mediated processes. Information available in this regard remains scarce. Using Escherichia coli (E. coli) as a model bacterium, we investigated the effect of kaolinite on various growth parameters. This clay mineral significantly affected maximal growth rate and yield of the E. coli-strain (MG 1655)

Elise Courvoisier; Sam Dukan

2009-01-01

26

Escherichia coli O157 and Children  

MedlinePLUS

ADVICE FOR PATIENTS Escherichia coli O157 and Children E scherichia coli is a common bacterium that is normally present in the human intestine. There ... illness is bloody diarrhea. SYMPTOMS AND SIGNS OF E COLI INFECTION •Severe stomach cramps •Diarrhea (often bloody) •Vomiting • ...

27

An Escherichia coli biosensor capable of detecting both genotoxic and oxidative damage  

Microsoft Academic Search

A two-plasmid dual reporter Escherichia coli biosensor was developed using the genes for bacterial bioluminescence and a mutant of the green fluorescent protein, GFPuv4. To achieve this, the two plasmids, which were derivatives of pBR322 and pACYC184, had compatible origins of replication and different antibiotic selection markers: ampicillin and tetracycline. The parent strains DK1 and ACRG43, each carrying a single

R. J. Mitchell; M. B. Gu

2004-01-01

28

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 PMID:4597449

Tso, Wung-Wai; Adler, Julius

1974-01-01

29

Recombinant collagen production optimization in Escherichia coli  

E-print Network

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

Whittemore, Brett A

2005-01-01

30

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

31

Escherichia coli survival in waters: Temperature dependence  

EPA Science Inventory

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

32

Murein segregation in Escherichia coli.  

PubMed Central

Peptidoglycan (murein) segregation has been studied by means of a new labeling method. The method relies on the ability of Escherichia coli cells to incorporate D-Cys into macromolecular murein. The incorporation depends on a periplasmic amino acid exchange reaction. At low concentrations, D-Cys is innocuous to the cell. The distribution of modified murein in purified sacculi can be traced and visualized by immunodetection of the -SH groups by fluorescence and electron microscopy techniques. Analysis of murein segregation in wild-type and cell division mutant strains revealed that murein in polar caps is metabolically inert and is segregated in a conservative fashion. Elongation of the sacculus apparently occurs by diffuse insertion of precursors over the cylindrical part of the cell surface. At the initiation of cell division, there is a FtsZ-dependent localized activation of murein synthesis at the potential division sites. Penicillin-binding protein 3 and the products of the division genes ftsA and ftsQ are dispensable for the activation of division sites. As a consequence, under restrictive conditions ftsA,ftsI,or ftsQ mutants generate filamentous sacculi with rings of all-new murein at the positions where septa would otherwise develop. PMID:9139895

de Pedro, M A; Quintela, J C; Höltje, J V; Schwarz, H

1997-01-01

33

Succinate production in Escherichia coli  

PubMed Central

Succinate has been recognized as an important platform chemical that can be produced from biomass. While a number of organisms are capable of succinate production naturally, this review focuses on the engineering of Escherichia coli for production of the four-carbon dicarboxylic acid. Important features of a succinate production system are to achieve optimal balance of reducing equivalents generated by consumption of the feedstock, while maximizing the amount of carbon that is channeled to the product. Aerobic and anaerobic production strains have been developed and applied to production from glucose as well as other abundant carbon sources. Metabolic engineering methods and strain evolution have been used and supplemented by the recent application of systems biology and in silico modeling tools to construct optimal production strains. The metabolic capacity of the production strain, as well as the requirement for efficient recovery of succinate and the reliability of the performance under scale-up are important in the overall process. The costs of the overall biorefinery compatible process will determine the economical commercialization of succinate and its impact in larger chemical markets. PMID:21932253

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

2012-01-01

34

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

2012-02-01

35

EM2006K-33 revised Identification of forces shaping the commensal Escherichia coli  

E-print Network

1 EM2006K-33 revised Identification of forces shaping the commensal Escherichia coli genetic title: Commensal Escherichia coli ecological structure Key words: Escherichia coli, commensal, animal forces shaping the Escherichia coli intraspecies ecological structure, we have characterized in terms

36

In-stream Escherichia coli Modeling  

NASA Astrophysics Data System (ADS)

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

Pandey, P.; Soupir, M.

2013-12-01

37

Budget Analysis of Escherichia coli at a Southern Lake Michigan  

E-print Network

Budget Analysis of Escherichia coli at a Southern Lake Michigan Beach P R A M O D T H U P A K I, 2009. Escherichia coli (EC) concentrations at two beaches impacted by river plume dynamics in southern bacteria such as Escherichia coli (EC) and enterococci (1). Coastal water quality has a significant

38

Parallel Evolutionary Dynamics of Adaptive Diversification in Escherichia coli  

E-print Network

Parallel Evolutionary Dynamics of Adaptive Diversification in Escherichia coli Matthew D. Herron1 sources caused initially isogenic populations of the bacterium Escherichia coli to diversify into two Diversification in Escherichia coli. PLoS Biol 11(2): e1001490. doi:10.1371/ journal.pbio.1001490 Academic Editor

Doebeli, Michael

39

FtsZ From Escherichia coli, Azotobacter vinelandii, and Thermotoga  

E-print Network

FtsZ From Escherichia coli, Azotobacter vinelandii, and Thermotoga maritima--Quantitation, GTP and Azotobacter vinelandii and expressed the proteins (TmFtsZ and AzFtsZ) in Escherichia coli. We compared as well, as Escherichia coli FtsZ (EcFtsZ) can assemble in vitro into protofilament sheets with a lattice

Erickson, Harold P.

40

ORIGINAL ARTICLE Escherichia coli transcription factor YncC  

E-print Network

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

Wood, Thomas K.

41

Four products from Escherichia coli pseudogenes increase hydrogen production q  

E-print Network

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

Wood, Thomas K.

42

Miniseries: Illustrating the Machinery of Life Escherichia coli*  

E-print Network

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

Economou, Tassos

43

Research Note--Prevalence of Pathogenic Escherichia coli in the  

E-print Network

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

Singer, Randall

44

Secretory Production of Human Leptin in Escherichia coli  

E-print Network

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

45

Proteomic analysis of thioredoxin-targeted proteins in Escherichia coli  

E-print Network

Proteomic analysis of thioredoxin-targeted proteins in Escherichia coli Jaya K. Kumar, Stanley present a comprehensive analysis of the thioredoxin-linked Escherichia coli proteome by using tandem in a reaction catalyzed by thioredoxin reductase (4). Originally isolated from Escherichia coli in 1964

Richardson, Charles C.

46

DETECTING ENTEROPATHOGENIC ESCHERICHIA COLI STRAINS OF PORCINE ORIGIN  

E-print Network

DETECTING ENTEROPATHOGENIC ESCHERICHIA COLI STRAINS OF PORCINE ORIGIN 1. Correlations between 0 VILLEJUIF, France _ Résumé DEPISTAGE DES SOUCHES D'ESCHERICHIA COLI ENTEROPATHOGENES D'ORIGINE PORGINE. - 1 tests biologiques (cellules Y1 et souriceau nouveau-né) à partir de 67 souches d'Escherichia coli

Boyer, Edmond

47

Light-powering Escherichia coli with proteorhodopsin Jessica M. Walter*  

E-print Network

Light-powering Escherichia coli with proteorhodopsin Jessica M. Walter* , Derek Greenfield respira- tion is inhibited by depleting oxygen or by the respiratory poison azide, Escherichia coli cells cellular pmf and, thus, viability. Proteorhodopsin allows Escherichia coli cells to withstand environmental

Liphardt, Jan

48

Molecular Archaeology of the Escherichia coli Genome  

Microsoft Academic Search

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

Jeffrey G. Lawrence; Howard Ochman

1998-01-01

49

Post-irradiation Recovery of Escherichia coli  

Microsoft Academic Search

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

J. S. Lee; R. O. Sinnhuber

1965-01-01

50

Escherichia Coli--Key to Modern Genetics.  

ERIC Educational Resources Information Center

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

Bregegere, Francois

1982-01-01

51

Sexually transmitted Escherichia coli urethritis and orchiepididymitis.  

PubMed

We describe herein a case of uropathogenic Escherichia coli urethritis and orchiepididymitis in a heterosexual man, which he had acquired sexually from his girlfriend. The identity of the genital isolates from both partners was confirmed by pulsed-field gel electrophoresis. PMID:22183838

Dan, Michael; Gottesman, Tamar; Schwartz, Orna; Tsivian, Alexander; Gophna, Uri; Rokney, Assaf

2012-01-01

52

Leaner and meaner genomes in Escherichia coli.  

PubMed

A 'better' Escherichia coli K-12 genome has recently been engineered in which about 15% of the genome has been removed by planned deletions. Comparison with related bacterial genomes that have undergone a natural reduction in size suggests that there is plenty of scope for yet more deletions. PMID:17076878

Ussery, David W

2006-01-01

53

Drug-resistant Diarrheogenic Escherichia coli, Mexico  

PubMed Central

Diarrheogenic Escherichia coli isolates from 45 (73%) of 62 hospitalized patients were resistant to common antimicrobial drugs. Sixty-two percent were multidrug resistant, and >70% were resistant to trimethoprim-sulfamethoxazole and ampicillin. Ciprofloxacin and cefotaxime were uniformly active. Effective and safe oral agents are needed to treat children with bacterial diarrhea. PMID:16102327

Cerna, Jorge F.; Paheco-Gil, Leova; Velázquez, Raúl F.; Ochoa, Theresa J.; Torres, Javier; DuPont, Herbert L.

2005-01-01

54

Escherichia coli in Europe: An Overview  

PubMed Central

Escherichia coli remains one of the most frequent causes of several common bacterial infections in humans and animals. E. coli is the prominent cause of enteritis, urinary tract infection, septicaemia and other clinical infections, such as neonatal meningitis. E. coli is also prominently associated with diarrhoea in pet and farm animals. The therapeutic treatment of E. coli infections is threatened by the emergence of antimicrobial resistance. The prevalence of multidrug-resistant E. coli strains is increasing worldwide principally due to the spread of mobile genetic elements, such as plasmids. The rise of multidrug-resistant strains of E. coli also occurs in Europe. Therefore, the spread of resistance in E. coli is an increasing public health concern in European countries. This paper summarizes the current status of E. coli strains clinically relevant in European countries. Furthermore, therapeutic interventions and strategies to prevent and control infections are presented and discussed. The article also provides an overview of the current knowledge concerning promising alternative therapies against E. coli diseases. PMID:24287850

Allocati, Nerino; Masulli, Michele; Alexeyev, Mikhail F.; Di Ilio, Carmine

2013-01-01

55

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

PubMed Central

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

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

2013-01-01

56

Dissolution of silver nanowires and nanospheres dictates their toxicity to Escherichia coli.  

PubMed

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

Visnapuu, Meeri; Joost, Urmas; Juganson, Katre; Künnis-Beres, Kai; Kahru, Anne; Kisand, Vambola; Ivask, Angela

2013-01-01

57

Controlling the Shape of Filamentous Cells of Escherichia coli  

E-print Network

Controlling the Shape of Filamentous Cells of Escherichia coli Shoji Takeuchi,, Willow R. Di of Escherichia coli with defined shapes, including crescents, zigzags, sinusoids, and spirals. The procedure into solution. This paper describes a technique for controlling the shape of filamentous cells of Escherichia

Weibel, Douglas B.

58

Hydrogen production by recombinant Escherichia coli strains  

PubMed Central

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

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

2012-01-01

59

Escherichia coli as a genetic tool.  

PubMed Central

The study of Escherichia coli and its plasmids and bacteriophages has provided a vast body of genetical information, much of it relevant to the whole of biology. This was true even before the development of the new techniques, for cloning and analysing DNA, that have revolutionized biological research during the past decade. Thousands of millions of dollars are now invested in industrial uses of these techniques, which all depend on discoveries made in the course of academic research on E. coli. Much of the background of knowledge necessary for the cloning and expression of genetically engineered information, as well as the techniques themselves, came from work with this organism. PMID:3005394

Datta, N.

1985-01-01

60

Motility influences biofilm architecture in Escherichia coli  

Microsoft Academic Search

Eight Escherichia coli strains were studied in minimal medium with a continuous flow system using confocal microscopy. K12 wild-type strains ATCC 25404 and MG1655 formed the best biofilms (?43 ?m thick, 21 to 34% surface coverage). JM109, DH5?, and MG1655 motA formed intermediate biofilms (?13 ?m thick, 41 to 58% surface coverage). BW25113, MG1655 qseB, and MG1655 fliA had poor biofilms (surface

Thomas K. Wood; Andrés F. González Barrios; Moshe Herzberg; Jintae Lee

2006-01-01

61

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

62

Structureactivity relationship of fluoroquinolone in Escherichia coli  

Microsoft Academic Search

Structure-activity relationship of 20 fluoroquinolones was studied using the susceptible and 4 resistantEscherichia coli which were developed against 4 fluoroquinolones [ciprofloxacin (1), KR-10755 (6), norfloxacin (2), and ofloxacin (3)] in\\u000a our laboratory. The C-7 and C-8 substituents of fluoroquinolone were important in various functions such as the inhibitory\\u000a activity on DNA gyrase, permeability, and efflux. Among 20 fluoroquinolones, compounds with

Soondeuk Lee; Taeho Park; Yeonhee Lee

1998-01-01

63

Natural plasmid transformation in Escherichia coli.  

PubMed

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 cells and plating again on selective agar plates. Competence developed in the lag phase, but disappeared during exponential growth. As more plasmids were added to the cell suspension, the number of transformants increased, eventually reaching a plateau. Supercoiled monomeric or linear concatemeric DNA could transform cells, while linear monomeric DNA could not. Plasmid transformation was not related to conjugation and was recA-independent. Most of the E. coli strains surveyed had this process. All tested plasmids, except pACYC184, could transform E. coli. Insertion of a DNA fragment containing the ampicillin resistance gene into pACYC184 made the plasmid transformable. By inserting random 20-base-pair oligonucleotides into pACYC184 and selecting for transformable plasmids, a most frequent sequence was identified. This sequence resembled the bacterial interspersed medium repetitive sequence of E. coli, suggesting the existence of a recognition sequence. We conclude that plasmid natural transformation exists in E. coli. PMID:12065899

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

2002-01-01

64

21 CFR 866.3255 - Escherichia coli serological reagents.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3255 Escherichia coli serological reagents. (a) Identification....

2011-04-01

65

COMPARATIVE RESISTANCE OF ESCHERICHIA COLI AND ENTEROCOCCI TO CHLORINATION  

EPA Science Inventory

Pure cultures of Escherichia coli and Enterococcus faecium were inactivated by free chlorine and monochloramine. ndigenous E. coli and enterococci in wastewater effluents were also inactivated. elective bacteriological media specifically designed for the enumeration of the target...

66

Biodegradation of Aromatic Compounds by Escherichia coli  

PubMed Central

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

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

2001-01-01

67

[Transformation of phosphotransferase system in Escherichia coli].  

PubMed

We constructed several recombinant Escherichia coli strains to transform phosphoenolpyruvate: carbohydrate phosphotransferase system (PTS system) and compared the characteristics of growth and metabolism of the mutants. We knocked-out the key genes ptsI and ptsG in PTS system by using Red homologous recombination in E. coli and meanwhile we also knocked-in the glucose facilitator gene glf from Zymomonas mobilis in the E. coli chromosome. Recombinant E. coli strains were constructed and the effects of cell growth, glucose consumption and acetic acid accumulation were also evaluated in all recombinant strains. The deletion of gene ptsG and ptsI inactivated some PTS system functions and inhibited the growth ability of the cell. Expressing the gene glf can help recombinant E. coli strains re-absorb the glucose through Glf-Glk (glucose facilitator-glucokinase) pathway as it can use ATP to phosphorylate glucose and transport into cell. This pathway can improve the availability of glucose and also reduce the accumulation of acetic acid; it can also broaden the carbon flux in the metabolism pathway. PMID:25726581

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

2014-10-01

68

Core and Panmetabolism in Escherichia coli? †  

PubMed Central

Escherichia coli exhibits a wide range of lifestyles encompassing commensalism and various pathogenic behaviors which its highly dynamic genome contributes to develop. How environmental and host factors shape the genetic structure of E. coli strains remains, however, largely unknown. Following a previous study of E. coli genomic diversity, we investigated its diversity at the metabolic level by building and analyzing the genome-scale metabolic networks of 29 E. coli strains (8 commensal and 21 pathogenic strains, including 6 Shigella strains). Using a tailor-made reconstruction strategy, we significantly improved the completeness and accuracy of the metabolic networks over default automatic reconstruction processes. Among the 1,545 reactions forming E. coli panmetabolism, 885 reactions were common to all strains. This high proportion of core reactions (57%) was found to be in sharp contrast to the low proportion (13%) of core genes in the E. coli pangenome, suggesting less diversity of metabolic functions compared to that of all gene functions. Core reactions were significantly overrepresented among biosynthetic reactions compared to the more variable degradation processes. Differences between metabolic networks were found to follow E. coli phylogeny rather than pathogenic phenotypes, except for Shigella networks, which were significantly more distant from the others. This suggests that most metabolic changes in non-Shigella strains were not driven by their pathogenic phenotypes. Using a supervised method, we were yet able to identify small sets of reactions related to pathogenicity or commensalism. The quality of our reconstructed networks also makes them reliable bases for building metabolic models. PMID:21239590

Vieira, Gilles; Sabarly, Victor; Bourguignon, Pierre-Yves; Durot, Maxime; Le Fèvre, François; Mornico, Damien; Vallenet, David; Bouvet, Odile; Denamur, Erick; Schachter, Vincent; Médigue, Claudine

2011-01-01

69

S-Nitrosylation Signaling in Escherichia coli  

NSDL National Science Digital Library

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

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

2012-06-12

70

Fluoroquinolone-resistant Escherichia coli, Indonesia  

PubMed Central

In a recent, population-based survey of 3,996 persons in Indonesia, fluoroquinolone (FQ)-resistant Escherichia coli was prevalent in the fecal flora of 6% of patients at hospital admission and 23% of patients at discharge, but not among healthy relatives or patients visiting primary healthcare centers (2%). Molecular typing showed extensive genetic diversity with only limited clonality among isolates. This finding suggests that independent selection of resistant mutants occurs frequently. FQ-resistant isolates exhibited a higher rate of spontaneous mutation, but sparser virulence profiles, than FQ-susceptible isolates from the same population. The resistant isolates belonged predominantly to phylogenetic groups A (57%) and B1 (22%) but also to the moderately virulent group D (20%). Hypervirulent strains from the B2 cluster were underrepresented (1%). Because FQ-resistant E. coli can cause disease, especially nosocomial infections in immunocompromised patients, spread of such strains must be stopped. PMID:16229763

Kuntaman, Kuntaman; Lestari, Endang Sri; Severin, Juliëtte A.; Kershof, Irma M.; Mertaniasih, Ni Made; Purwanta, Marijam; Hadi, Usman; Johnson, James R.; Verbrugh, Henri A.

2005-01-01

71

Escherichia coli growth under modeled reduced gravity  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

72

Accumulation of Tetracyclines by Escherichia coli  

PubMed Central

The net accumulation of tetracyclines by Escherichia coli as a function of concentration was shown to be biphasic. At concentrations less than the bacteriostatic levels, the mode of uptake was not azide-sensitive and was considered to be physical adsorption on the cell surface. At concentrations above the minimal inhibitory level, a second, azide-sensitive, uptake component was functional in addition to the surface adsorption process. This second energy-requiring mode was judged to represent penetration of the cytoplasmic membrane by tetracycline molecules to their sites of inhibitory action. Each mode for a given tetracycline and culture is expressed algebraically by a characteristic Freundlich equation. Resistance in E. coli is shown to be a result of diminished transport of antibiotic. However, this resistance was due not to a reduction or loss of a transport mechanism but rather to a requirement for higher antibiotic concentrations before the second mode of uptake could become operative. PMID:4867743

De Zeeuw, John R.

1968-01-01

73

Engineering the Escherichia coli Fermentative Metabolism  

NASA Astrophysics Data System (ADS)

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

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

74

[DNA supercoiling and topoisomerases in Escherichia coli].  

PubMed

The chromosomal DNA of all cells is under helical tension or supercoiling. There are two classes of DNA supercoiling: plectonemic and toroidal. Plectonemic supercoiling is generated by the action of DNA topoisomerases, while toroidal supercoiling is generated by DNA-protein interactions and by topoisomerase activitities. DNA supercoiling plays an important role in replication, repair, recombination, transposition and transcription. DNA topoisomerases type I are ATP-independent enzymes that cut one DNA strand and relax supercoiled molecules. DNA topoisomerases type II requiere ATP, cut both DNA strands and supercoil relaxed molecules. All organisms have more than one topoisomerase of each, type I and type II. Escherichia coli has two topoisomerases type I: topoisomerase I and topoisomerase III and two topoisomerases type II: topoisomerase II or gyrase and topoisomerase IV. In this review we discuss the concept of DNA supercoiling and present current knowledge on E. coli DNA topoisomerases. PMID:8850348

Gómez-Eichelmann, M C; Camacho-Carranza, R

1995-01-01

75

Designed phosphoprotein recognition in Escherichia coli.  

PubMed

Protein phosphorylation is a central biological mechanism for cellular adaptation to environmental changes. Dysregulation of phosphorylation signaling is implicated in a wide variety of diseases. Thus, the ability to detect and quantify protein phosphorylation is highly desirable for both diagnostic and research applications. Here we present a general strategy for detecting phosphopeptide-protein interactions in Escherichia coli. We first redesign a model tetratricopeptide repeat (TPR) protein to recognize phosphoserine in a sequence-specific fashion and characterize the interaction with its target phosphopeptide in vitro. We then combine in vivo site-specific incorporation of phosphoserine with split mCherry assembly to observe the designed phosphopeptide-protein interaction specificity in E. coli. This in vivo strategy for detecting and characterizing phosphopeptide-protein interactions has numerous potential applications for the study of natural interactions and the design of novel ones. PMID:25272187

Sawyer, Nicholas; Gassaway, Brandon M; Haimovich, Adrian D; Isaacs, Farren J; Rinehart, Jesse; Regan, Lynne

2014-11-21

76

Complete Genome Sequence of Escherichia coli Strain BL21  

PubMed Central

Escherichia coli strain BL21 is one of the widely used bacterial hosts for high-level recombinant protein production and for other applications. Here, we present the complete genome sequence of a commercial version of the Escherichia coli BL21 strain. PMID:25792055

Kim, Hyun Ju; Lee, Sang Jun

2015-01-01

77

Escherichia coli antibodies in patients with inflammatory bowel disease  

Microsoft Academic Search

Sera from 30 patients with inflammatory bowel disease (IBD) (16 with Crohn's disease (CD) and 14 with ulcerative colitis (UC) were assayed for the presence of antibodies against 159 Escherichia coli O-antigens and compared with sera from 16 matched control subjects. The majority of patients with IBD had agglutinating antibodies to a higher number of Escherichia coli O-antigens and in

S Tabaqchali; D P ODonoghue; K A Bettelheim

1978-01-01

78

Chemical Organizations in the Central Sugar Metabolism of Escherichia Coli  

E-print Network

1 Chemical Organizations in the Central Sugar Metabolism of Escherichia Coli Florian Centler represent po- tential steady state compositions of the system. When applied to a model of sugar metabolism, network analysis, stoichiometry, systems biology, sugar metabolism, Escherichia coli 1.1 Introduction

Dittrich, Peter

79

Engineering Escherichia coli for methanol conversion.  

PubMed

Methylotrophic bacteria utilize methanol and other reduced one-carbon compounds as their sole source of carbon and energy. For this purpose, these bacteria evolved a number of specialized enzymes and pathways. Here, we used a synthetic biology approach to select and introduce a set of "methylotrophy genes" into Escherichia coli based on in silico considerations and flux balance analysis to enable methanol dissimilation and assimilation. We determined that the most promising approach allowing the utilization of methanol was the implementation of NAD-dependent methanol dehydrogenase and the establishment of the ribulose monophosphate cycle by expressing the genes for hexulose-6-phosphate synthase (Hps) and 6-phospho-3-hexuloisomerase (Phi). To test for the best-performing enzymes in the heterologous host, a number of enzyme candidates from different donor organisms were selected and systematically analyzed for their in vitro and in vivo activities in E. coli. Among these, Mdh2, Hps and Phi originating from Bacillus methanolicus were found to be the most effective. Labeling experiments using (13)C methanol with E. coli producing these enzymes showed up to 40% incorporation of methanol into central metabolites. The presence of the endogenous glutathione-dependent formaldehyde oxidation pathway of E. coli did not adversely affect the methanol conversion rate. Taken together, the results of this study represent a major advancement towards establishing synthetic methylotrophs by gene transfer. PMID:25596507

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

2015-03-01

80

Production of glycoprotein vaccines in Escherichia coli  

PubMed Central

Background Conjugate vaccines in which polysaccharide antigens are covalently linked to carrier proteins belong to the most effective and safest vaccines against bacterial pathogens. State-of-the art production of conjugate vaccines using chemical methods is a laborious, multi-step process. In vivo enzymatic coupling using the general glycosylation pathway of Campylobacter jejuni in recombinant Escherichia coli has been suggested as a simpler method for producing conjugate vaccines. In this study we describe the in vivo biosynthesis of two novel conjugate vaccine candidates against Shigella dysenteriae type 1, an important bacterial pathogen causing severe gastro-intestinal disease states mainly in developing countries. Results Two different periplasmic carrier proteins, AcrA from C. jejuni and a toxoid form of Pseudomonas aeruginosa exotoxin were glycosylated with Shigella O antigens in E. coli. Starting from shake flask cultivation in standard complex medium a lab-scale fed-batch process was developed for glycoconjugate production. It was found that efficiency of glycosylation but not carrier protein expression was highly susceptible to the physiological state at induction. After induction glycoconjugates generally appeared later than unglycosylated carrier protein, suggesting that glycosylation was the rate-limiting step for synthesis of conjugate vaccines in E. coli. Glycoconjugate synthesis, in particular expression of oligosaccharyltransferase PglB, strongly inhibited growth of E. coli cells after induction, making it necessary to separate biomass growth and recombinant protein expression phases. With a simple pulse and linear feed strategy and the use of semi-defined glycerol medium, volumetric glycoconjugate yield was increased 30 to 50-fold. Conclusions The presented data demonstrate that glycosylated proteins can be produced in recombinant E. coli at a larger scale. The described methodologies constitute an important step towards cost-effective in vivo production of conjugate vaccines, which in future may be used for combating severe infectious diseases, particularly in developing countries. PMID:20701771

2010-01-01

81

Sources of Escherichia coli in a Coastal Subtropical Environment  

Microsoft Academic Search

Sources of Escherichia coli in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in E. coli concentrations as well as experiments conducted under laboratory-controlled conditions. E. coli from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling

HELENA M. SOLO-GABRIELE; MELINDA A. WOLFERT; TIMOTHY R. DESMARAIS; CAROL J. PALMER

2000-01-01

82

Phylogenetic Analysis of Enteroaggregative and Diffusely Adherent Escherichia coli  

Microsoft Academic Search

The phylogenetics of the various pathotypes of diarrheagenic Escherichia coli are not completely understood. In this study, we identified several plasmid and chromosomal genes in the pathogenic enteroaggregative E. coli (EAEC) prototype strain 042 and determined the prevalence of these loci among EAEC and diffusely adherent E. coli strains. The distribution of these genes is analyzed within an evolutionary framework

JOHN R. CZECZULIN; THOMAS S. WHITTAM; IAN R. HENDERSON; FERNANDO NAVARRO-GARCIA; JAMES P. NATARO

1999-01-01

83

Review article Secretion of virulence factors by Escherichia coli  

E-print Network

Review article Secretion of virulence factors by Escherichia coli Bernard China* Fréderic Goffaux with their host, pathogenic strains of E. coli need to secrete some virulence factors which can modify the metabolism of host cells, contributing to disease. Since E. coli is a Gram-negative bacteria, this secretion

Paris-Sud XI, Université de

84

Engineering a Reduced Escherichia coli Genome  

PubMed Central

Our goal is to construct an improved Escherichia coli to serve both as a better model organism and as a more useful technological tool for genome science. We developed techniques for precise genomic surgery and applied them to deleting the largest K-islands of E. coli, identified by comparative genomics as recent horizontal acquisitions to the genome. They are loaded with cryptic prophages, transposons, damaged genes, and genes of unknown function. Our method leaves no scars or markers behind and can be applied sequentially. Twelve K-islands were successfully deleted, resulting in an 8.1% reduced genome size, a 9.3% reduction of gene count, and elimination of 24 of the 44 transposable elements of E. coli. These are particularly detrimental because they can mutagenize the genome or transpose into clones being propagated for sequencing, as happened in 18 places of the draft human genome sequence. We found no change in the growth rate on minimal medium, confirming the nonessential nature of these islands. This demonstration of feasibility opens the way for constructing a maximally reduced strain, which will provide a clean background for functional genomics studies, a more efficient background for use in biotechnology applications, and a unique tool for studies of genome stability and evolution. [Sequence data described in this paper have been submitted to the DNA Data Bank of Japan, European Molecular Biology Laboratory, and GenBank databases under accession nos. AF402780, AF402779, and AF406953, respectively.] PMID:11932248

Kolisnychenko, Vitaliy; Plunkett, Guy; Herring, Christopher D.; Fehér, Tamás; Pósfai, János; Blattner, Frederick R.; Pósfai, György

2002-01-01

85

Comparison of 61 sequenced Escherichia coli genomes.  

PubMed

Escherichia coli is an important component of the biosphere and is an ideal model for studies of processes involved in bacterial genome evolution. Sixty-one publically available E. coli and Shigella spp. sequenced genomes are compared, using basic methods to produce phylogenetic and proteomics trees, and to identify the pan- and core genomes of this set of sequenced strains. A hierarchical clustering of variable genes allowed clear separation of the strains into clusters, including known pathotypes; clinically relevant serotypes can also be resolved in this way. In contrast, when in silico MLST was performed, many of the various strains appear jumbled and less well resolved. The predicted pan-genome comprises 15,741 gene families, and only 993 (6%) of the families are represented in every genome, comprising the core genome. The variable or 'accessory' genes thus make up more than 90% of the pan-genome and about 80% of a typical genome; some of these variable genes tend to be co-localized on genomic islands. The diversity within the species E. coli, and the overlap in gene content between this and related species, suggests a continuum rather than sharp species borders in this group of Enterobacteriaceae. PMID:20623278

Lukjancenko, Oksana; Wassenaar, Trudy M; Ussery, David W

2010-11-01

86

Comparison of 61 Sequenced Escherichia coli Genomes  

PubMed Central

Escherichia coli is an important component of the biosphere and is an ideal model for studies of processes involved in bacterial genome evolution. Sixty-one publically available E. coli and Shigella spp. sequenced genomes are compared, using basic methods to produce phylogenetic and proteomics trees, and to identify the pan- and core genomes of this set of sequenced strains. A hierarchical clustering of variable genes allowed clear separation of the strains into clusters, including known pathotypes; clinically relevant serotypes can also be resolved in this way. In contrast, when in silico MLST was performed, many of the various strains appear jumbled and less well resolved. The predicted pan-genome comprises 15,741 gene families, and only 993 (6%) of the families are represented in every genome, comprising the core genome. The variable or ‘accessory’ genes thus make up more than 90% of the pan-genome and about 80% of a typical genome; some of these variable genes tend to be co-localized on genomic islands. The diversity within the species E. coli, and the overlap in gene content between this and related species, suggests a continuum rather than sharp species borders in this group of Enterobacteriaceae. PMID:20623278

Lukjancenko, Oksana; Wassenaar, Trudy M.

2010-01-01

87

STUDIES ON THE LACTASE OF ESCHERICHIA COLI.  

PubMed

A "lactase solution" was prepared from Escherichia coli. The mechanism of its action has been studied and changes in the rate of hydrolysis under various conditions investigated. The hydrolysis of lactose by the enzyme approximates the course of reaction of the integrated Michaelis-Menten equation. One molecule of enzyme combines with one molecule of substrate. E. coli lactase is readily inactivated at pH 5.0, and its optimal activity at 36 degrees C. is reached between pH 7.0 and pH 7.5. The optimal temperature for its action was found to be 46 degrees C. when determinations were carried out after an incubation period of 30 minutes. Its inactivation by heat follows the course of a first order reaction, and the critical thermal increment between the temperatures of 45 degrees C. and 53 degrees C. was calculated to be 56,400 calories per mol. The enzyme is activated by potassium cyanide, sodium sulfide, and cysteine, and irreversibly inactivated by mercuric chloride, silver nitrate, and iodine. After inactivation with copper sulfate partial reactivation is possible, while the slight inhibition brought about by hydrogen peroxide is completely reversible. The possible structure of the active groups of E. coli lactase as compared with other enzymes has been discussed. PMID:19873223

Knopfmacher, H P; Salle, A J

1941-01-20

88

Guanylate kinase of Escherichia coli K-12.  

PubMed

We have identified the gene gmk, in the same operon as rpoZ, spoT, and recG at about 82 minutes on the Escherichia coli chromosome. The gmk (GMP kinase) gene encodes a peptide of 23,592 Da, possessing extensive similarity to the amino acid sequence of guanylate kinase from yeast. To confirm that gmk truly encodes guanylate kinase and to explore some of its enzymatic features, we have overproduced the product of gmk and purified it to homogeneity. Unlike guanylate kinases purified from eukaryotic sources, E. coli guanylate kinase is multimeric, and ionic conditions dictate its protomeric state; under low ionic conditions it appears to be a tetramer while under high ionic conditions it is a dimer. Kinetic analysis reveals that guanylate kinase, again, unlike eukaryotic guanylate kinases, binds GMP cooperatively and that the observed cooperatively changes with ionic strength. These results indicate that, despite extensive sequence similarity to its eukaryotic counterparts, E. coli guanylate kinase is structurally and enzymatically different. PMID:8390989

Gentry, D; Bengra, C; Ikehara, K; Cashel, M

1993-07-01

89

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

90

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

E-print Network

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

91

Pathogenic Escherichia coli strain discrimination using laser-induced breakdown spectroscopy  

E-print Network

Pathogenic Escherichia coli strain discrimination using laser-induced breakdown spectroscopy A pathogenic strain of bacteria, Escherichia coli O157:H7 enterohemorrhagic E. coli or EHEC , has been analyzed with both nanosecond and femtosecond laser pulses to identify the Escherichia coli bacterium.10­12 E. coli

Rehse, Steven J.

92

Dispensability of Escherichia coli's latent pathways  

E-print Network

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

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

2011-01-01

93

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

E-print Network

Evolution of transcription factors and the gene regulatory network in Escherichia coli M. Madan Escherichia coli. In order to gain insight into the evolution of the E.coli regula- tory network, we analysed

Babu, M. Madan

94

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. PMID:2181258

Van Houten, B

1990-01-01

95

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

2013-04-01

96

Chemotaxis Toward Sugars in Escherichia coli  

PubMed Central

Using a quantitative assay for measuring chemotaxis, we tested a variety of sugars and sugar derivatives for their ability to attract Escherichia coli bacteria. The most effective attractants, i.e., those that have thresholds near 10?5 M or below, are N-acetyl-d-glucosamine, 6-deoxy-d-glucose, d-fructose, d-fucose, 1-d-glycerol-?-d-galactoside, galactitol, d-galactose, d-glucosamine, d-glucose, ?-d-glucose-1-phosphate, lactose, maltose, d-mannitol, d-mannose, methyl-?-d-galactoside, methyl-?-d-glucoside, d-ribose, d-sorbitol, and trehalose. Lactose, and probably d-glucose-1-phosphate, are attractive only after conversion to the free monosaccharide, while the other attractants do not require breakdown for taxis. Nine different chemoreceptors are involved in detecting these various attractants. They are called the N-acetyl-glucosamine, fructose, galactose, glucose, maltose, mannitol, ribose, sorbitol, and trehalose chemoreceptors; the specificity of each was studied. The chemoreceptors, with the exception of the one for d-glucose, are inducible. The galactose-binding protein serves as the recognition component of the galactose chemoreceptor. E. coli also has osmotically shockable binding activities for maltose and d-ribose, and these appear to serve as the recognition components for the corresponding chemoreceptors. PMID:4580570

Adler, Julius; Hazelbauer, Gerald L.; Dahl, M. M.

1973-01-01

97

Induction of radioresistance in Escherichia coli.  

PubMed Central

The effect of prior treatment by inducing agents on the radioresistance of cells of Escherichia coli has been studied. In order to separate the induction process from the radiation-damage process, cells were first treated with inducing agents such as ultraviolet light, ionizing radiation, or nalidixic acid, allowed to become induced by incubation for 50 min and then given rifampin to prevent further induction. They were then tested for radiation sensitivity. It was found that all strains tested except recA-, lex-, and recB showed very apparent protection. Induction by UV had the most effect and by nalidixic acid the least. The time course of development of protection was observed in one case: it is 50% established in 15 min. The absence of effect in recA- and lex- is explainable by the fact that these cells cannot be induced, for example, for prophage or the inducible inhibitor of post-irradiation DNA degradation. We suggest that the inducible inhibitor of postirradiation DNA degradation is one factor in a recovery system possessed by E. coli cells. PMID:1103984

Pollard, E C; Achey, P M

1975-01-01

98

Independence of replisomes in Escherichia coli chromosomalreplication  

SciTech Connect

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

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

2005-03-13

99

Surface Expression of ?-Transaminase in Escherichia coli  

PubMed Central

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

Gustavsson, Martin; Muraleedharan, Madhu Nair

2014-01-01

100

The extracellular RNA complement of Escherichia coli  

PubMed Central

The secretion of biomolecules into the extracellular milieu is a common and well-conserved phenomenon in biology. In bacteria, secreted biomolecules are not only involved in intra-species communication but they also play roles in inter-kingdom exchanges and pathogenicity. To date, released products, such as small molecules, DNA, peptides, and proteins, have been well studied in bacteria. However, the bacterial extracellular RNA complement has so far not been comprehensively characterized. Here, we have analyzed, using a combination of physical characterization and high-throughput sequencing, the extracellular RNA complement of both outer membrane vesicle (OMV)-associated and OMV-free RNA of the enteric Gram-negative model bacterium Escherichia coli K-12 substrain MG1655 and have compared it to its intracellular RNA complement. Our results demonstrate that a large part of the extracellular RNA complement is in the size range between 15 and 40 nucleotides and is derived from specific intracellular RNAs. Furthermore, RNA is associated with OMVs and the relative abundances of RNA biotypes in the intracellular, OMV and OMV-free fractions are distinct. Apart from rRNA fragments, a significant portion of the extracellular RNA complement is composed of specific cleavage products of functionally important structural noncoding RNAs, including tRNAs, 4.5S RNA, 6S RNA, and tmRNA. In addition, the extracellular RNA pool includes RNA biotypes from cryptic prophages, intergenic, and coding regions, of which some are so far uncharacterised, for example, transcripts mapping to the fimA-fimL and ves-spy intergenic regions. Our study provides the first detailed characterization of the extracellular RNA complement of the enteric model bacterium E. coli. Analogous to findings in eukaryotes, our results suggest the selective export of specific RNA biotypes by E. coli, which in turn indicates a potential role for extracellular bacterial RNAs in intercellular communication. PMID:25611733

Ghosal, Anubrata; Upadhyaya, Bimal Babu; Fritz, Joëlle V; Heintz-Buschart, Anna; Desai, Mahesh S; Yusuf, Dilmurat; Huang, David; Baumuratov, Aidos; Wang, Kai; Galas, David; Wilmes, Paul

2015-01-01

101

Emergence of Fluoroquinolone Resistance in Outpatient Urinary Escherichia coli Isolates  

Microsoft Academic Search

BackgroundBecause of high rates of trimethoprim-sulfamethoxazole resistance in Escherichia coli, Denver Health switched to levofloxacin as the initial therapy for urinary tract infections (UTIs) in 1999. We evaluated the effects of that switch 6 years later.

Luke Johnson; Allison Sabel; William J. Burman; Rachel M. Everhart; Marcie Rome; Thomas D. MacKenzie; Jeanne Rozwadowski; Philip S. Mehler; Connie Savor Price

2008-01-01

102

TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI  

EPA Science Inventory

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

103

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

PubMed Central

Escherichia coli (E. coli), and particularly the adherent invasive E. coli (AIEC) pathotype, has been increasingly implicated in the ethiopathogenesis of Crohn’s disease (CD). E. coli strains with similar pathogenic features to AIEC have been associated with other intestinal disorders such as ulcerative colitis, colorectal cancer, and coeliac disease, but AIEC prevalence in these diseases remains largely unexplored. Since AIEC was described one decade ago, substantial progress has been made in deciphering its mechanisms of pathogenicity. However, the molecular bases that characterize the phenotypic properties of this pathotype are still not well resolved. A review of studies focused on E. coli populations in inflammatory bowel disease (IBD) is presented here and we discuss about the putative role of this species on each IBD subtype. Given the relevance of AIEC in CD pathogenesis, we present the latest research findings concerning AIEC host-microbe interactions and pathogenicity. We also review the existing data regarding the prevalence and abundance of AIEC in CD and its association with other intestinal diseases from humans and animals, in order to discuss the AIEC disease- and host-specificity. Finally, we highlight the fact that dietary components frequently found in industrialized countries may enhance AIEC colonization in the gut, which merits further investigation and the implementation of preventative measures. PMID:25133024

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

2014-01-01

104

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

105

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

106

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

SciTech Connect

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

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

1991-08-01

107

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...

108

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

109

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

110

Detection of Escherichia coli and Salmonella in chicken rinse carcasses  

Microsoft Academic Search

Purpose – This paper seeks to optimize a multiplex PCR in order to detect the incidence of Salmonella and Escherichia coli (E. coli) in chicken carcasses, eliminating a pre-culture enrichment step and the pathogen isolation. Design\\/methodology\\/approach – A total of 30 chicken rinse carcasses were analysed by standard microbiological methods, and the isolates were identified by biochemical and serological tests.

G. F. Asensi; E. M. F. dos Reis; E. M. Del Aguila; D. dos P. Rodrigues; J. T. Silva; V. M. F. Paschoalin

2009-01-01

111

ESCHERICHIA COLI O ANTIGEN TYPING USING DNA MICROARRAYS  

Technology Transfer Automated Retrieval System (TEKTRAN)

DNA microarrays were developed for rapid identification of different serogroups of Escherichia coli in a single platform. Oligonucleotides, as well as PCR products from genes in the O-antigen gene clusters of E. coli serogroups O7, O104, O111, and O157 were spotted onto glass slides. This was foll...

112

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

113

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

114

DETECTION OF ESCHERICHIA COLI 0157:H7 USING IMMUNO BEADS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A new fluorescent sandwich method for the detection of Escherichia coli O157:H7 was developed. Streptavidin-coated magnetic beads and fluorescence beads were used to react with biotinylated anti E. coli O157 antibodies to form the immuno magnetic beads (IMB) and immuno fluorescence beads (IFB), resp...

115

Curli Fibers Mediate Internalization of Escherichia coli by Eukaryotic Cells  

Microsoft Academic Search

Curli fibers are adhesive surface fibers expressed by Escherichia coli and Salmonella enterica that bind several host extracellular matrix and contact phase proteins and were assumed to have a role in pathogenesis. The results presented here suggest that one such role is internalization into host cells. An E. coli K-12 strain transformed with a low-copy vector containing the gene cluster

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

2001-01-01

116

Escherichia coli Response to Exogenous Pyrophosphate and Analogs  

Microsoft Academic Search

The addition of exogenous pyrophosphate increases the growth yield and cAMP synthesis in stationary phase when Escherichia coli is grown in minimal medium. Pyrophosphate increases the yield by altering the enterobactin uptake system. We studied the physiological effects and examined how the E. coli transcriptome was modified when two structural analogs of pyrophosphate were added to the growth medium. Methylenediphosphonic

Francis Biville; Taku Oshima; Hirotada Mori; Yuya Kawagoe; Odile Bouvet; Marie-Noëlle Rager; Marina Perrotte-Piquemal; Antoine Danchin

2003-01-01

117

Metabolomic and transcriptomic stress response of Escherichia coli  

Microsoft Academic Search

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

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

2010-01-01

118

Prevalence and antibiotic resistance of Escherichia coli in tropical seafood  

Microsoft Academic Search

Summary The occurrence and antibiotic resistance of Escherichia coli in tropical seafood was studied. A 3-tube MPN method was used for determining the level of faecal contamination of fresh and processed seafood. Of the 188 samples tested which included finfish, shellfish, water and ice, 155 were positive for the presence of faecal coliforms following incubation at 44.5 °C. However, E. coli

H. S. Kumar; A. Parvathi; I. Karunasagar

2005-01-01

119

Mutual Enhancement of Virulence by Enterotoxigenic and Enteropathogenic Escherichia coli  

Microsoft Academic Search

Enterotoxigenic Escherichia coli (ETEC) and enteropathogenic E. coli (EPEC) are common causes of diar- rhea in children in developing countries. Dual infections with both pathogens have been noted fairly frequently in studies of diarrhea around the world. In previous laboratory work, we noted that cholera toxin and forskolin markedly potentiated EPEC-induced ATP release from the host cell, and this potentiated

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

2006-01-01

120

The Escherichia coli Peripheral Inner Membrane Proteome*  

PubMed Central

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

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

2013-01-01

121

The N-degradome of Escherichia coli  

PubMed Central

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

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

2013-01-01

122

Methane production from kitchen waste using Escherichia coli.  

PubMed

Escherichia coli (E. coli) strain isolated from biogas plant sludge was examined for its ability to enhance biogas from kitchen waste during solid phase anaerobic digestion. The laboratory experiments were conducted for total solid concentrations of 20% and 22%. Kitchen waste was characterized for physico-chemical parameters and laboratory experiments were conducted with and without E. coli strain. It was found that the reactor with E. coli produced 17% more biogas than the reactors that are operated without E. coli strain. PMID:18476402

Jayalakshmi, S; Joseph, Kurian; Sukumaran, V

2007-04-01

123

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

E-print Network

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

124

Carbon monoxide prevents apoptosis induced by uropathogenic Escherichia coli toxins  

Microsoft Academic Search

Urinary tract infections (UTIs) are often caused by Escherichia coli (E. coli). Previous studies have demonstrated that up-regulation of heme oxygenase-1 (HO-1) may trigger a survival mechanism against renal cell death induced by E. coli toxins. The present study analyses the role of carbon monoxide (CO), an end product of HO-1, in the survival mechanism. Moreover, we identified hemolysin as

Ming Chen; Roshan Tofighi; Wenjie Bao; Olle Aspevall; Timo Jahnukainen; Lars E. Gustafsson; Sandra Ceccatelli; Gianni Celsi

2006-01-01

125

Recovery of recombinant Escherichia coli by chitosan-conjugated magnetite  

Microsoft Academic Search

Magnetic separation of a recombinant Escherichia coli harboring the ?-galactosidase gene was investigated. We prepared a chitosan-conjugated magnetite (chitosan-mag) that disperses well in aqueous solution. After adding it to a cell suspension, it can recover various microorganisms including E. coli as the precipitant within only 1min. Over 90% of E. coli cells were recovered in a wide pH range from

Hiroyuki Honda; Atsushi Kawabe; Masashige Shinkai; Takeshi Kobayashi

1999-01-01

126

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

127

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

128

Regulation of the Escherichia coli lrp gene.  

PubMed Central

Lrp (leucine-responsive regulatory protein) is a major Escherichia coli regulatory protein which regulates expression of a number of operons, some negatively and some positively. This work relates to a characterization of lrp, the gene encoding Lrp. Nucleotide sequencing established that the coding regions of lrp and trxB (encoding thioredoxin reductase) are separated by 543 bp and that the two genes are transcribed in opposite directions. In addition, we used primer extension, deletion analyses, and lrp-lacZ transcriptional fusions to delineate the promoter and regulatory region of the lrp operon. The lrp promoter is located 267 nucleotides upstream of the translational start codon of the lrp gene. In comparison with a wild-type strain, expression of the lrp operon was increased about 3-fold in a strain lacking Lrp and decreased about 10-fold in a strain overproducing Lrp. As observed from DNA mobility shift and DNase I footprinting analyses, Lrp binds to one or more sites within the region -80 to -32 relative to the start point of lrp transcription. A mutational analysis indicated that this same region is at least partly required for repression of lrp expression in vivo. These results demonstrate that autogenous regulation of lrp involves Lrp acting directly to cause repression of lrp transcription. Images PMID:8144448

Wang, Q; Wu, J; Friedberg, D; Plakto, J; Calvo, J M

1994-01-01

129

Membrane cytochromes of Escherichia coli chl mutants.  

PubMed Central

The cytochromes present in the membranes of Escherichia coli cells having defects in the formate dehydrogenase-nitrate reductase system have been analyzed by spectroscopic, redox titration, and enzyme fractionation techniques. Four phenotypic classes differing in cytochrome composition were recognized. Class I is represented by strains with defects in the synthesis or insertion of molybdenum cofactor. Cytochromes of the formate dehydrogenase-nitrate reductase pathway are present. Class II strains map in the chlC-chlI region. The cytochrome associated with nitrate reductase (cytochrome bnr) is absent in these strains, whereas that associated with formate dehydrogenase (cytochrome bfdh) is the major cytochrome in the membranes. Class III strains lack both cytochromes bfdh and bnr but overproduce cytochrome d of the aerobic pathway even under anaerobic conditions in the presence of nitrate. Class III strains have defects in the regulation of cytochrome synthesis. An fdhA mutant produced cytochrome bnr but lacked cytochrome bfdh. These results support the view that chlI (narI) is the structural gene for cytochrome bnr and that chlC (narG) and chlI(narI) are in the same operon, and they provide evidence of the complexity of the regulation of cytochrome synthesis. PMID:6302081

Hackett, N R; Bragg, P D

1983-01-01

130

Regulation of alcohol fermentation by Escherichia coli  

SciTech Connect

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

Clark, D.P.

1986-03-01

131

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 PMID:7968921

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

1994-01-01

132

Virulence regulons of enterotoxigenic Escherichia coli.  

PubMed

Enterotoxigenic Escherichia coli is frequently associated with travelers' diarrhea and is a leading cause of infant and childhood mortality in developing countries. Disease is dependent upon the orchestrated expression of enterotoxins, flexible adhesive pili, and other virulence factors. Both the heat-labile (LT) and heat-stable (ST-H) enterotoxins are regulated at the level of transcription by cAMP-receptor protein which represses the expression of LT while activating expression of ST-H. The expression of many different serotypes of adhesive pili is regulated by Rns, a member of the AraC family that represents a subgroup of conserved virulence regulators from several enteric pathogens. These Rns-like regulators recognize similar DNA binding sites, and a compiled sequence logo suggests they may bind DNA through both major and minor groove interactions. These regulators are also tempting targets for novel therapeutics because they play pivotal roles during infection. To that end, high-throughput screens have begun to identify compounds that inhibit the activity of these regulators, predominately by interfering with DNA binding. PMID:24203442

Munson, George P

2013-12-01

133

Colonization factors of enterotoxigenic Escherichia coli.  

PubMed

Enterotoxigenic Escherichia coli (ETEC) is a major cause of life-threatening diarrheal disease around the world. The major aspects of ETEC virulence are colonization of the small intestine and the secretion of enterotoxins which elicit diarrhea. Intestinal colonization is mediated, in part, by adhesins displayed on the bacterial cell surface. As colonization of the intestine is the critical first step in the establishment of an infection, it represents a potential point of intervention for the prevention of infections. Therefore, colonization factors (CFs) have been important subjects of research in the field of ETEC virulence. Research in this field has revealed that ETEC possesses a large array of serologically distinct CFs that differ in composition, structure, and function. Most ETEC CFs are pili (fimbriae) or related fibrous structures, while other adhesins are simple outer membrane proteins lacking any macromolecular structure. This chapter reviews the genetics, structure, function, and regulation of ETEC CFs and how such studies have contributed to our understanding of ETEC virulence and opened up potential opportunities for the development of preventive and therapeutic interventions. PMID:25596032

Madhavan, T P Vipin; Sakellaris, Harry

2015-01-01

134

Mutagenesis in Escherichia coli lacking catalase.  

PubMed

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

Abril, N; Pueyo, C

1990-01-01

135

Caenorhabditis elegans as a simple model to study phenotypic and genetic virulence determinants of extraintestinal pathogenic Escherichia coli strains  

E-print Network

of extraintestinal pathogenic Escherichia coli strains Caenorhabditis elegans as a simple model to study phenotypic and genotypic determinants of pathogenicity of extraintestinal pathogenic Escherichia coli Virulence of extraintestinal pathogenic Escherichia coli strains in Caenorhabditis elegans Virulence of extraintestinal

Paris-Sud XI, Université de

136

First report of Escherichia coli O157 among Iraqi children.  

PubMed

We determined the prevalence of enterohaemorrhagic Escherichia coli, especially E. coli O157, and other enteropathogens among 200 children with bloody diarrhoea and 100 age-matched controls at two Baghdad hospitals. Bacterial and parasitic agents were found in 39.5% and 28.5% of cases, respectively; no pathogen was detected in 32%. E. coli O157 was identified in 11.5% and more than one pathogen was found in 15.5% of cases. The most common pathogens were enteropathogenic E. coli (EPEC) (5%); E. coli other than E. coli O157 or EPEC (15%); Entamoeba histolytica (25%) and Giardia lamblia (3.5%). All isolates of E. coli O157:H7 were sensitive to cephalexin, ciprofloxacin, gentamicin and nalidixic acid and resistant to erythromycin, polymyxin B and vancomycin. Resistance to 6 or more antimicrobial agents was common (50% of isolates). PMID:15562746

Shebib, Z A; Abdul Ghani, Z G; Mahdi, L Kh

2003-01-01

137

Rapid Sterilization of Escherichia coli by Solution Plasma Process  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

138

Binding specificity of Escherichia coli trigger factor  

PubMed Central

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

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

2001-01-01

139

S-Methylmethionine Metabolism in Escherichia coli  

PubMed Central

Selenium-accumulating Astragalus spp. contain an enzyme which specifically transfers a methyl group from S-methylmethionine to the selenol of selenocysteine, thus converting it to a nontoxic, since nonproteinogenic, amino acid. Analysis of the amino acid sequence of this enzyme revealed that Escherichia coli possesses a protein (YagD) which shares high sequence similarity with the enzyme. The properties and physiological role of YagD were investigated. YagD is an S-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate. Mutants in yagD which also possess defects in metE and metH are unable to utilize S-methylmethionine for growth, whereas a metE metH double mutant still grows on S-methylmethionine. Upstream of yagD and overlapping with its reading frame is a gene (ykfD) which, when inactivated, also blocks growth on methylmethionine in a metE metH genetic background. Since it displays sequence similarities with amino acid permeases it appears to be the transporter for S-methylmethionine. Methionine but not S-methylmethionine in the medium reduces the amount of yagD protein. This and the existence of four MET box motifs upstream of yfkD indicate that the two genes are members of the methionine regulon. The physiological roles of the ykfD and yagD products appear to reside in the acquisition of S-methylmethionine, which is an abundant plant product, and its utilization for methionine biosynthesis. PMID:9882684

Thanbichler, Martin; Neuhierl, Bernhard; Böck, August

1999-01-01

140

Expression of enteropathogenic Escherichia coli map is significantly different than that of other type III secreted effectors in vivo.  

PubMed

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

Nguyen, Mai; Rizvi, Jason; Hecht, Gail

2015-01-01

141

Review article Pathogenic diversity of Escherichia coli  

E-print Network

and systemic infections in humans and other animals. The spectrum of diseases caused by E. coli is due termed pathogenicity islands (PAls) that are absent from the genomes of commen- sal E. coli strains. PAls are likely to have been transferred horizontally and may have integrated into the E. coli chromosome through

Boyer, Edmond

142

Oligomerization of the lysr-type transcriptional regulators in Escherichia Coli  

E-print Network

....................................................................................... 101 V RESISTANCE TO METHOTREXATE DUE TO AcrAB- DEPENDENT EXPORT FROM Escherichia coli............................... 103 Overview ........................................................................................ 103...

Knapp, Gwendowlyn Sue

2009-05-15

143

A Genome-Wide Analysis of Promoter-Mediated Phenotypic Noise in Escherichia coli  

E-print Network

A Genome-Wide Analysis of Promoter-Mediated Phenotypic Noise in Escherichia coli Olin K. Silander1 with genes' functional attributes, using data for over 60% of all promoters in Escherichia coli. We find in Escherichia coli. PLoS Genet 8(1): e1002443. doi:10.1371/journal.pgen.1002443 Editor: Ivan Matic, Universite

Zhang, Jianzhi

144

ENZYMATIC PROCESSING OF REPLICATION INTERMEDIATES THAT OCCUR FOLLOWING UV-INDUCED DNA DAMAGE IN ESCHERICHIA COLI  

E-print Network

IN ESCHERICHIA COLI By Janet Renee Donaldson A Dissertation Submitted to the Faculty of Mississippi State PROCESSING OF REPLICATION INTERMEDIATES THAT OCCUR FOLLOWING UV-INDUCED DNA DAMAGE IN ESCHERICHIA COLI PROCESSING OF REPLICATION INTERMEDIATES THAT OCCUR FOLLOWING UV-INDUCED DNA DAMAGE IN ESCHERICHIA COLI Pages

Courcelle, Justin

145

Cofactor Binding to Escherichia coli D-3-Phosphoglycerate Dehydrogenase Induces Multiple Conformations Which Alter  

E-print Network

Cofactor Binding to Escherichia coli D-3-Phosphoglycerate Dehydrogenase Induces Multiple of Medicine, St. Louis, Missouri 63110 The inhibition of Escherichia coli D-3-phosphoglycer- ate dehydrogenase (PGDH, EC 1.1.1.95)1 from Escherichia coli catalyzes the first committed step in the phosphorylated

Grant, Gregory

146

Iron limitation induces SpoT-dependent accumulation of ppGpp in Escherichia coli  

E-print Network

Iron limitation induces SpoT-dependent accumulation of ppGpp in Escherichia coli D. Vinella1*, C Summary In Escherichia coli the -lactam mecillinam specifically inhibits penicillin-binding protein 2 (PBP the limitation. #12;3 juin 8, 2006 Introduction The Gram negative bacterium Escherichia coli has evolved various

Paris-Sud XI, Université de

147

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

E-print Network

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

Peletier, Mark

148

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

E-print Network

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

Wood, Thomas K.

149

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

E-print Network

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

Selinger, Brent

150

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

E-print Network

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

Chattopadhyay, Sujay

151

ESCHERICHIA COLI ISOLATED FROM CALVES WITH DIARRHŒA: MANNOSE-RESISTANT HAEMAGGLUTINATION  

E-print Network

ESCHERICHIA COLI ISOLATED FROM CALVES WITH DIARRHŒA: MANNOSE-RESISTANT HAEMAGGLUTINATION souches de Escherichia coli isolées des veaux diarrhéiques. La détection de l'antigène K99, en 84 souches de Escherichia coli, a été effectuée par le Brush-Border, l'hémagglutination avec et sans mannose et

Paris-Sud XI, Université de

152

SLECTION ET PERSISTANCE, DANS LA FLORE FCALE DE VEAUX DE BOUCHERIE, DE ESCHERICHIA COLI  

E-print Network

SÉLECTION ET PERSISTANCE, DANS LA FLORE FÉCALE DE VEAUX DE BOUCHERIE, DE ESCHERICHIA COLI RÉSISTANT of oxytetracycline on the resistance of fecal Escherichia coli to the following antibacterial agents: ampicillin (Ap flore fécale, de souches d'Escherichia coli résistantes à cet antibiotique (Mitsuhashi, 1979). Ces sou

Paris-Sud XI, Université de

153

Motility of Escherichia coli cells in clusters formed by chemotactic aggregation  

E-print Network

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

van Oudenaarden, Alexander

154

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

E-print Network

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

Meir, Yigal

155

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

E-print Network

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

Chen, Wilfred

156

Brief Original Article Multiple contaminations of chickens with Campylobacter, Escherichia coli  

E-print Network

Brief Original Article Multiple contaminations of chickens with Campylobacter, Escherichia coli, Escherichia coli, and Salmonella are mainly caused by the consumption of raw or undercooked poultry meat. The objective of this study was to evaluate the prevalence of Campylobacter, Escherichia coli, and Salmonella

Paris-Sud XI, Université de

157

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

E-print Network

Escherichia coli: a brief review of diarrheagenic pathotypes and their role in diarrheal diseases, Tehran. 2 Bacteriology Department, Pasteur Institute of Iran, Tehran. 3 National Escherichia coli, Aslani MM Address: Molecular Biology Unit, Pasteur Institute of Iran. National Escherichia coli Reference

Paris-Sud XI, Université de

158

Measuring the forces involved in polyvalent adhesion of uropathogenic Escherichia coli to  

E-print Network

Measuring the forces involved in polyvalent adhesion of uropathogenic Escherichia coli to mannose from the interaction of uropathogenic Escherichia coli to molecularly well defined models of cellular, Escherichia coli [the primary causative agent of urinary tract infections (3, 4)] use the FimH adhesin located

Prentiss, Mara

159

ORIGINAL ARTICLE Identification of stress-related proteins in Escherichia coli  

E-print Network

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

Wood, Thomas K.

160

Reprogramming of Escherichia coli K-12 Metabolism during the Initial Phase of Transition from an Anaerobic  

E-print Network

Reprogramming of Escherichia coli K-12 Metabolism during the Initial Phase of Transition from anaerobe Escherichia coli K-12 provides an ideal system for exploring this process. Methods and Findings) Reprogramming of Escherichia coli K-12 Metabolism during the Initial Phase of Transition from an Anaerobic

Williamson, Mike P.

161

Cattle water troughs as reservoirs of Escherichia coli O157.  

PubMed

Environmental survival of Escherichia coli O157 may play an important role in the persistence and dissemination of this organism on farms. The survival of culturable and infectious E. coli O157 was studied using microcosms simulating cattle water troughs. Culturable E. coli O157 survived for at least 245 days in the microcosm sediments. Furthermore, E. coli O157 strains surviving more than 6 months in contaminated microcosms were infectious to a group of 10-week-old calves. Fecal excretion of E. coli O157 by these calves persisted for 87 days after challenge. Water trough sediments contaminated with feces from cattle excreting E. coli O157 may serve as a long-term reservoir of this organism on farms and a source of infection for cattle. PMID:11425721

LeJeune, J T; Besser, T E; Hancock, D D

2001-07-01

162

Cattle Water Troughs as Reservoirs of Escherichia coli O157  

PubMed Central

Environmental survival of Escherichia coli O157 may play an important role in the persistence and dissemination of this organism on farms. The survival of culturable and infectious E. coli O157 was studied using microcosms simulating cattle water troughs. Culturable E. coli O157 survived for at least 245 days in the microcosm sediments. Furthermore, E. coli O157 strains surviving more than 6 months in contaminated microcosms were infectious to a group of 10-week-old calves. Fecal excretion of E. coli O157 by these calves persisted for 87 days after challenge. Water trough sediments contaminated with feces from cattle excreting E. coli O157 may serve as a long-term reservoir of this organism on farms and a source of infection for cattle. PMID:11425721

LeJeune, Jeffrey T.; Besser, Thomas E.; Hancock, Dale D.

2001-01-01

163

Demonstration of exopolysaccharide production by enterohemorrhagic Escherichia coli  

Microsoft Academic Search

EnterohemorrhagicEscherichia coli O157:H7 produces visibly slimy colonies when grown on Sorbitol\\/MacConkey or Maloney's agar plates at room temperature, indicative of exopolysaccharide (EPS) production. Eighteen of 27 (67%) wild-typeE. coli O157:H7 isolates produced enough EPS to be visually distinguishable. Of five strains that showed no visible EPS production on these media, four (80%) did produce slimy colonies on media containing higher

Alan D. Junkins; Michael P. Doyle

1992-01-01

164

Differentiation of Escherichia coli Pathotypes by Oligonucleotide Spotted Array  

Microsoft Academic Search

Received 27 July 2005\\/Returned for modification 28 September 2005\\/Accepted 11 January 2006 To accurately determine the pathotypes of Escherichia coli strains, a comprehensive assessment of each strain that targets multiple genes is required. A new approach to the identification and characterization of E. coli pathotypes was developed by constructing gene-specific probes (70-mers) for not only the virulence genes associated with

Raghavan U. M. Palaniappan; Yu Zhang; David Chiu; Alfonso Torres; Chobi DebRoy; Thomas S. Whittam; Yung-Fu Chang

2006-01-01

165

Expression of biologically active recombinant equine interferon-? in Escherichia coli  

Microsoft Academic Search

Interferon gamma (IFN-?) is a pleiotropic cytokine that is recognized as an important modulator of the immune response. To date, there is no report that prokaryocyte-derived recombinant equine IFN-? has antiviral activity. In this report, the gene coding equine IFN-? (EIFN-?) mature protein was cloned into pET-28a (+) and the recombinant EIFN-? was expressed in Escherichia coli (E. coli). The

Yu Bai; Tiegang Tong; Guangliang Liu; Weiye Chen; Weijun Zhang; Qun Wang; Tao Yang; Zhigao Bu; Donglai Wu

2010-01-01

166

Display of green fluorescent protein on Escherichia coli cell surface  

Microsoft Academic Search

In this study, expression of green fluorescence protein (GFP) on the external surface of Escherichia coli was achieved by construction of a fusion protein between Lpp-OmpA hybrid and a GFP variant, GFPmut2. The GFP was fused in frame to the carboxyl-terminus of Lpp-OmpA fusion previously shown to direct various other heterologous proteins to E. coli cell surface. Western blot analysis

Huidong Shi; Wei Wen Su

2001-01-01

167

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

168

The Complete Genome Sequence of Escherichia coli K-12  

Microsoft Academic Search

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

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

2007-01-01

169

Characterization of fluoroquinolone resistance in Escherichia coli strains from ruminants  

Microsoft Academic Search

Thirty-seven fluoroquinolone-resistant Escherichia coli strains from ruminants (according to Clinical and Laboratory Standards Institute guidelines) were screened by molecular methods for mutations in the quinolone resistance-determining region (QRDR) of the gyrA and parC genes and for the presence of the qnrA gene. One of the strains studied was an enterohemorrhagic E. coli (EHEC) strain potentially pathogenic for humans. Three E.

Sonia Jurado; Pilar Horcajo

2008-01-01

170

Deactivation of Escherichia coli by the plasma needle  

Microsoft Academic Search

In this paper we present a parameter study on deactivation of Escherichia coli (E. coli) by means of a non-thermal plasma (plasma needle). The plasma needle is a small-sized (1 mm) atmospheric glow sustained by radio-frequency excitation. This plasma will be used to disinfect heat-sensitive objects; one of the intended applications is in vivo deactivation of dental bacteria: destruction of

R. E. J. Sladek; E. Stoffels

2005-01-01

171

AVIAN DISEASES 46:4852, 2002 Virulence Factors of Escherichia coli from Cellulitis or  

E-print Network

48 AVIAN DISEASES 46:48­52, 2002 Virulence Factors of Escherichia coli from Cellulitis. This study was designed to compare virulence factors of cellulitis-derived Escherichia coli to colisepticemic E. coli in order to clarify whether E. coli associated with cellulitis comprise a unique subset

Singer, Randall

172

Escherichia coli K88 adhesion : A comparison of Chinese and Large White piglets  

E-print Network

Note Escherichia coli K88 adhesion : A comparison of Chinese and Large White piglets J.P. CHAPPUIS : K88 adhesion, E. coli, pig, genetic resistance. Résumé L'attachement de Escherichia coli K88, maintained in plastic film isolators. Shortly after successive oral inoculations of 2 E. coli strains, one K

Paris-Sud XI, Université de

173

Multidrug-resistant Escherichia coli in Asia: epidemiology and management.  

PubMed

Escherichia coli has become multiresistant by way of production of a variety of ?-lactamases. The prevalence of CTX-M-producing E. coli has reached 60-79% in certain parts of Asia. The acquisition of CTX-M plasmids by E. coli sequence type 131, a successful clone of E. coli, has caused further dissemination of CTX-M-producing E. coli. The prevalence of carbapenemase-producing E. coli, especially Klebsiella pneumoniae carbapenemase, and New Delhi metallo-?-lactamase (NDM)-producing E. coli has been increasing in Asia. K. pneumoniae carbapenemase and NDM have now been found in E. coli sequence type 131. The occurrence of NDM-producing E. coli is a major concern particularly in the Indian subcontinent, but now elsewhere in Asia as well. There are multiple reasons why antibiotic resistance in E. coli in Asia has reached such extreme levels. Approaches beyond antibiotic therapy, such as prevention of antibiotic resistance by antibiotic stewardship and protecting natural microbiome, are strategies to avoid further spread of antibiotic resistance. PMID:25805210

Sidjabat, Hanna E; Paterson, David L

2015-05-01

174

Bacteriophage conversion of heat-labile enterotoxin in Escherichia coli.  

PubMed Central

A temperate phage designated obeta1 (omicron beta) was mitomycin C induced and isolated from heat-labile enterotoxin (LT)-producing Escherichia coli E2631-C2. Phage obeta1 infected the nonlysogenic, nontoxigenic, mitomycin C-sensitive strain of E. coli K-12 (CSH38) and converted it to lysogeny and enterotoxigenicity. After the establishment of lysogeny, E. coli CSH38(obeta1) produced produced LT and phage particles at maximal levels following mitomycin C induction. The LT Tox+ character is carried by the temperate phage obeta1. PMID:338578

Takeda, Y; Murphy, J R

1978-01-01

175

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

176

YeeO from Escherichia coli exports flavins.  

PubMed

Multidrug and toxic compound extrusion (MATE) proteins help maintain cellular homeostasis by secreting metabolic wastes. Flavins may occur as cellular waste products, with their production and secretion providing potential benefit for industrial applications related to biofuel cells. Here we find that MATE protein YeeO from Escherichia coli exports both flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Significant amounts of flavins were trapped intracellularly when YeeO was produced indicating transport limits secretion of flavins. Wild-type E. coli secreted 3 flavins (riboflavin, FMN, and FAD), so E. coli likely produces additional flavin transporters. PMID:25482085

McAnulty, Michael J; Wood, Thomas K

2014-01-01

177

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

PubMed Central

Molecular studies of enzymes involved in sulfite oxidation in Acidithiobacillus ferrooxidans have not yet been developed, especially in the ATP sulfurylase (ATPS) of these acidophilus tiobacilli that have importance in biomining. This enzyme synthesizes ATP and sulfate from adenosine phosphosulfate (APS) and pyrophosphate (PPi), final stage of the sulfite oxidation by these organisms in order to obtain energy. The atpS gene (1674 bp) encoding the ATPS from Acidithiobacillus ferrooxidans ATCC 23270 was amplified using PCR, cloned in the pET101-TOPO plasmid, sequenced and expressed in Escherichia coli obtaining a 63.5 kDa ATPS recombinant protein according to SDS-PAGE analysis. The bioinformatics and phylogenetic analyses determined that the ATPS from A. ferrooxidans presents ATP sulfurylase (ATS) and APS kinase (ASK) domains similar to ATPS of Aquifex aeolicus, probably of a more ancestral origin. Enzyme activity towards ATP formation was determined by quantification of ATP formed from E. coli cell extracts, using a bioluminescence assay based on light emission by the luciferase enzyme. Our results demonstrate that the recombinant ATP sulfurylase from A. ferrooxidans presents an enzymatic activity for the formation of ATP and sulfate, and possibly is a bifunctional enzyme due to its high homology to the ASK domain from A. aeolicus and true kinases. PMID:23055613

Jaramillo, Michael L; Abanto, Michel; Quispe, Ruth L; Calderón, Julio; del Valle, Luís J; Talledo, Miguel; Ramírez, Pablo

2012-01-01

178

A rapid BOD sensing system using luminescent recombinants of Escherichia coli.  

PubMed

A biochemical oxygen demand (BOD) sensing system based on bacterial luminescence from recombinant Escherichia coli containing lux A-E genes from Vibrio fischeri has been developed. It was possible to use frozen cells of luminescent recombinants of E. coli as the bacterial reagents for measurement. Steady bioluminescence was observed during the incubation time between 90 and 150 min in the presence of a sole carbon source such as glucose, acetate, L-glutamate and BOD standard solution (GGA solution). This disposable bacterial reagent was applied to measure and detect organic pollution due to biodegradable substances in various wastewaters. The obtained values of this study showed a similar correlation with that of the conventional method for BOD determination (BOD5). Bacterial luminescence that was visualized with an imaging system using a charge coupled device (CCD) camera and a photomulti-counter demonstrated that this method could also be used for multi-sample detection of organic pollution due to biodegradable substances by using a microtiter plate. These results suggested for successful achievement of high-though-put detection of BOD in practical. PMID:14568711

Sakaguchi, Toshifumi; Kitagawa, Kei; Ando, Tomotsugu; Murakami, Yuji; Morita, Yasutaka; Yamamura, Akira; Yokoyama, Kenji; Tamiya, Eiichi

2003-11-15

179

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

180

Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance  

E-print Network

Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance Nicole Salmonella typhimurium increases its antibiotic toler- ance in response to indole, even though S. typhimurium might be detected and used by both commensal and pathogenic bacteria. Although there is increasing

Collins, James J.

181

Recombinant protein folding and misfolding in Escherichia coli  

Microsoft Academic Search

The past 20 years have seen enormous progress in the understanding of the mechanisms used by the enteric bacterium Escherichia coli to promote protein folding, support protein translocation and handle protein misfolding. Insights from these studies have been exploited to tackle the problems of inclusion body formation, proteolytic degradation and disulfide bond generation that have long impeded the production of

Mirna Mujacic; François Baneyx

2004-01-01

182

Escherichia coli antibodies in patients with inflammatory bowel disease.  

PubMed Central

Sera from 30 patients with inflammatory bowel disease (IBD) (16 with Crohn's disease (CD) and 14 with ulcerative colitis (UC) were assayed for the presence of antibodies against 159 Escherichia coli O-antigens and compared with sera from 16 matched control subjects. The majority of patients with IBD had agglutinating antibodies to a higher number of Escherichia coli O-antigens and in higher titres than the control group. The number of positive agglutinins was O-33 mean 13.8 in CD, O-26 mean 7.9 for UC, and O-7 mean 1.5 in controls. Eight patients with IBD and arthropathy had antibodies to fewer O-antigens (O-7 mean 3.2). The antibodies were in the IgG and IgM, in titres corresponding to original values. No specific O-serotypes were associated with IBD. Common serotypes, R-plasmid carrying serotypes, and those associated with shigella-like adult diarrhoea were detected. O14 was detected only in five patients and O119 in none. There was no correlation between the number of Escherichia coli agglutinins and the site and severity of the disease or type of therapy. It is suggested that the presence of the high numbers of Escherichia coli antibodies is secondary to the disease process and is unlikely to be causally involved in the pathogenesis of the disease, but may play a role in the perpetuation of the disease and in the extraintestinal complications. PMID:344155

Tabaqchali, S; O'Donoghue, D P; Bettelheim, K A

1978-01-01

183

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

184

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

PubMed Central

Enteropathogenic Escherichia coli (EPEC) strains continue to cause severe and sometimes fatal infantile diarrhea, particularly in Africa. Increased efforts at diagnosis, defining the clinical spectrum of disease, understanding pathogenic mechanisms, and delineating immune responses are desperately needed to develop new strategies to combat EPEC. PMID:23815982

Donnenberg, Michael S.; Finlay, B. Brett

2015-01-01

185

Original article Resistance of Escherichia coli growing as biofilms  

E-print Network

Original article Resistance of Escherichia coli growing as biofilms to disinfectants C Ntsama) Summary ― The bactericidal activity of various disinfectants (cationic or amphoteric surfactants in a continuous culture system. The bacteria tested on germ-carriers or included in biofilms were more resistant

Boyer, Edmond

186

Original article Inhibition of Escherichia coli O157:H7  

E-print Network

and indigenous lactic acid bacteria (LAB) and the survival of Escherichia coli O157:H7 in fermented goat's milk (LP) system has been reported to inhibit the production of acid by lactic starter cultures and can result in the survival and growth of acid-adapted enteropathogens in LP-activated fermented milk. The aim

Paris-Sud XI, Université de

187

DNA cloning by homologous recombination in Escherichia coli  

Microsoft Academic Search

The cloning of foreign DNA in Escherichia coli episomes is a cornerstone of molecular biology. The pioneering work in the early 1970s, using DNA ligases to paste DNA into episomal vectors, is still the most widely used approach. Here we describe a different principle, using ET recombination, for directed cloning and subcloning, which offers a variety of advantages. Most prominently,

Youming Zhang; Joep P. P. Muyrers; Giuseppe Testa; A. Francis Stewart

2000-01-01

188

Protein Mobility in the Cytoplasm of Escherichia coli  

Microsoft Academic Search

The rate of protein diffusion in bacterial cytoplasm may constrain a variety of cellular functions and limit the rates of many biochemical reactions in vivo. In this paper, we report noninvasive measurements of the apparent diffusion coefficient of green fluorescent protein (GFP) in the cytoplasm of Escherichia coli. These measurements were made in two ways: by photobleaching of GFP fluorescence

MICHAEL B. ELOWITZ; MICHAEL G. SURETTE; PIERRE-ETIENNE WOLF; JEFFRY B. STOCK; STANISLAS LEIBLER

1999-01-01

189

Clocking Out: Modeling Phage-Induced Lysis of Escherichia coli  

Microsoft Academic Search

Phage lyses the host Escherichia coli at a precisely scheduled time after induction. Lysis timing is determined by the action of phage holins, which are small proteins that induce hole formation in the bacterium's cytoplasmic membrane. We present a two-stage nucleation model of lysis timing, with the nucle- ation of condensed holin rafts on the inner membrane followed by the

Gillian L. Ryan; Andrew D. Rutenberg

2007-01-01

190

Secretory and extracellular production of recombinant proteins using Escherichia coli  

Microsoft Academic Search

Escherichia coli is one of the most widely used hosts for the production of recombinant proteins. However, there are often problems in recovering substantial yields of correctly folded proteins. One approach to solve these problems is to have recombinant proteins secreted into the periplasmic space or culture medium. The secretory production of recombinant proteins has several advantages, such as simplicity

J. H. Choi; S. Y. Lee

2004-01-01

191

Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation.  

EPA Science Inventory

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

192

Temperature Affects Stoichiometry and Biochemical Composition of Escherichia coli  

Microsoft Academic Search

Temperature is a master variable controlling biochemical processes in organisms, and its effects are manifested on many organizational levels in organisms and ecosystems. We examined the effects of temperature on the biochemical composition and stoichiometry of a model heterotrophic bacterium, Escherichia coli K-12, held at constant growth rate in chemostats. Increasing temperature led to increased cellular organic carbon (C) and

James B. Cotner; Wataru Makino; Bopaiah A. Biddanda

2006-01-01

193

Molecular basis of base substitution hotspots in Escherichia coli  

Microsoft Academic Search

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

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

1978-01-01

194

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

195

Nontoxicity of an oil shale process water to Escherichia coli.  

PubMed

The survival of Escherichia coli in the presence of an oil shale process water was studied over a five day period. The organism survived better in the presence of one or ten percent concentration of the process water than it did in distilled or tap water. Water chemistry of the diluent appeared to be important to the survival of the organism. PMID:3892236

Adams, J C

1985-04-01

196

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

197

Pathway Choice in Glutamate Synthesis in Escherichia coli  

Microsoft Academic Search

Escherichia coli has two primary pathways for glutamate synthesis. The glutamine synthetase-glutamate synthase (GOGAT) pathway is essential for synthesis at low ammonium concentration and for regulation of the glutamine pool. The glutamate dehydrogenase (GDH) pathway is important during glucose-limited growth. It has been hypothesized that GDH is favored when the organism is stressed for energy, because the enzyme does not

ROBERT B. HELLING

1998-01-01

198

Microcalorimetric study on the aerobic growth of Escherichia coli  

Microsoft Academic Search

By using an LKB-2277 Bioactivity Monitor, complete thermograms of aerobic growth at 37°C have been obtained for Escherichia coli. The amount of glucose consumed Sc has been measured by the glucose oxidase method, and its relationship with the quantities of heat evolved Qt has been studied. Different linear relationships exist at different phases of Qt and Sc, indicating that there

Chang Li Xie; Hong Wang; Song Sheng Qu

1995-01-01

199

Global Functional Atlas of Escherichia coli Encompassing Previously Uncharacterized  

E-print Network

of Escherichia coli K-12 remain functionally unannotated (orphans). Many map to distant clades such as Archaea pathogenic strains. To elucidate the orphans' biological roles, we performed an extensive proteomic survey probabilistic networks revealed putative orphan membership in discrete multiprotein complexes and functional

Sheldon, Nathan D.

200

|Research Focus In search of the minimal Escherichia coli genome  

E-print Network

for a `second human genome project' to compile an inventory of the genomes of the human microflora, Stanley|Research Focus In search of the minimal Escherichia coli genome Darren J. Smalley, Marvin Whiteley and Tyrrell Conway Advanced Center for Genome Technology, The University of Oklahoma, Norman, OK 73019

Conway, Tyrrell

201

Complete Genome Sequence of Enterotoxigenic Escherichia coli Siphophage Seurat  

PubMed Central

Enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of diarrhea in developing countries. Bacteriophage therapy has the potential to aid in the prevention and treatment of ETEC-related illness. To that end, we present here the complete genome of ETEC siphophage Seurat and describe its major features. PMID:25720682

Doan, Dung P.; Lessor, Lauren E.; Hernandez, Adriana C.

2015-01-01

202

An SOS Response Induced by High Pressure in Escherichia coli  

Microsoft Academic Search

Although pressure is an important environmental parameter in microbial niches such as the deep sea and is furthermore used in food preservation to inactivate microorganisms, the fundamental understanding of its effects on bacteria remains fragmentary. Our group recently initiated differential fluorescence induction screening to search for pressure-induced Escherichia coli promoters and has already reported induction of the heat shock regulon.

Abram Aertsen; Rob Van Houdt; Kristof Vanoirbeek; Chris W. Michiels

2004-01-01

203

SOS Response Induces Persistence to Fluoroquinolones in Escherichia coli  

Microsoft Academic Search

Bacteria can survive antibiotic treatment without acquiring heritable antibiotic resistance. We investigated persistence to the fluoroquinolone ciprofloxacin in Escherichia coli. Our data show that a majority of persisters to ciprofloxacin were formed upon exposure to the antibiotic, in a manner dependent on the SOS gene network. These findings reveal an active and inducible mechanism of persister formation mediated by the

Tobias Dörr; Kim Lewis; Marin Vulic ´

2009-01-01

204

Lethal effect of ? DNA terminase in recombination deficient Escherichia coli  

Microsoft Academic Search

? DNA terminase is the enzyme that catalyses the cleavage of ? DNA concatemers into genome-size molecules and packages them into the capsid. The cleavage (DNA maturation) takes place in a specific site in the phage DNA called cos. Either one of two Escherichia coli proteins, integration host factor (IHF) and terminase host factor (THF), is required, in addition to

Helios Murialdo

1988-01-01

205

Spontaneous mutagenesis associated with nucleotide excision repair in Escherichia coli  

Microsoft Academic Search

The vast majority of spontaneous mutations occurring in Escherichia coli are thought to be derived from spontaneous DNA lesions, which include oxidative base damage. Systems for removing intrinsic mutagens and repairing DNA lesions contribute to the suppression of spontaneous mutations. Nucleotide excision repair (NER) is a general DNA repair system that eliminates various kinds of lesions from DNA. We therefore

Kimiko Hasegawa; Kaoru Yoshiyama; Hisaji Maki

2008-01-01

206

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

207

PCR-ELISA detection of Escherichia coli in milk  

Microsoft Academic Search

P. D A L Y , T. C O L L I E R A N D S. D O Y L E. 2002. Aims: The purpose of this study was to develop a reliable molecular procedure for the detection of Escherichia coli in milk. Methods and Results: Robust and expeditious DNA extraction and PCR techniques were evaluated using Enzyme-Linked

P. Daly; T. Collier; S. Doyle

2002-01-01

208

Septicaemia caused by cysteine-requiring isolates of Escherichia coli  

Microsoft Academic Search

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

J. W. TAPSALL; C. J. McIVER

1986-01-01

209

Superoxide Imposes Leakage of Sulfite from Escherichia coli  

Microsoft Academic Search

Escherichia coli,which lacks the cytosolic superoxide dismutases, exhibits several nutritional auxotrophies when growing aerobically. The cysteine\\/methionine requirement, which is one of these, was previously shown to be due to leakage from the cells, and accumulation in the medium, of a metabolic intermediate on the biosynthetic route to these amino acids. The parental strain does not significantly accumulate this compound. It

Ludmil Benov; Irwin Fridovich

1997-01-01

210

Visualizing multiple constrictions in spheroidal Escherichia coli cells  

Microsoft Academic Search

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 achieved

Arieh Zaritsky; Anton Van Geel; Itzhak Fishov; Evelien Pas; Monica Einav; Conrad L. Woldringh

1999-01-01

211

The Kinetics of the Mating Process in Escherichia coli  

Microsoft Academic Search

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

W. HAYES

1957-01-01

212

Enteropathogenic Escherichia coli and life threatening chronic diarrhoea  

Microsoft Academic Search

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

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

1991-01-01

213

Invasive Escherichia coli are a feature of Crohn's disease  

Microsoft Academic Search

Crohn's disease (CD) and ulcerative colitis (UC) are idiopathic inflammatory conditions of the gut. Our goal was to investigate if invasive Escherichia coli strains were present in patients with inflammatory bowel disease (IBD). Bacterial strains were isolated from biopsy material obtained from normal controls, and patients with a clinical diagnosis of CD and UC. Invasive bacteria were characterized by gentamicin

Maiko Sasaki; Shanti V Sitaraman; Brian A Babbin; Peter Gerner-Smidt; Efrain M Ribot; Nancy Garrett; Joel A Alpern; Adil Akyildiz; Arianne L Theiss; Asma Nusrat; Jan-Michael A Klapproth

2007-01-01

214

TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI  

EPA Science Inventory

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

215

Global Incidence of Carbapenemase-Producing Escherichia coli ST131  

PubMed Central

We characterized Escherichia coli ST131 isolates among 116 carbapenemase-producing strains. Of isolates from 16 countries collected during 2008–2013, 35% belonged to ST131 and were associated with blaKPC, H30 lineage, and virotype C. This study documents worldwide incidents of resistance to “last resort” antimicrobial drugs among a common pathogen in a successful sequence type. PMID:25340464

Peirano, Gisele; Bradford, Patricia A.; Kazmierczak, Krystyna M.; Badal, Robert E.; Hackel, Meredith; Hoban, Daryl J.

2014-01-01

216

Monitoring bacterial chemotaxis by using bioluminescence resonance energy transfer: Absence of feedback from the flagellar motors  

Microsoft Academic Search

We looked for a feedback system in Escherichia coli that might sense the rotational bias of flagellar motors and regulate the activity of the chemotaxis receptor kinase. Our search was based on the assumption that any machinery that senses rotational bias will be perturbed if flagellar rotation stops. We monitored the activity of the kinase in swimming cells by bioluminescence

Thomas S. Shimizu; Nicolas Delalez; Klemens Pichler; Howard C. Berg

2006-01-01

217

Homogeneous assay for biotin based on Aequorea victoria bioluminescence resonance energy transfer system  

Microsoft Academic Search

Here we describe a homogeneous assay for biotin based on bioluminescence resonance energy transfer (BRET) between aequorin and enhanced green fluorescent protein (EGFP). The fusions of aequorin with streptavidin (SAV) and EGFP with biotin carboxyl carrier protein (BCCP) were purified after expression of the corresponding genes in Escherichia coli cells. Association of SAV–aequorin and BCCP–EGFP fusions was followed by BRET

Andrey Yu Gorokhovatsky; Natalia V Rudenko; Victor V Marchenkov; Vitaly S Skosyrev; Maxim A Arzhanov; Nils Burkhardt; Mikhail V Zakharov; Gennady V Semisotnov; Leonid M Vinokurov; Yuli B Alakhov

2003-01-01

218

Monitoring Bacterial Chemotaxis by Using Bioluminescence Resonance Energy Transfer: Absence of Feedback from the Flagellar Motors  

Microsoft Academic Search

We looked for a feedback system in Escherichia coli that might sense the rotational bias of flagellar motors and regulate the activity of the chemotaxis receptor kinase. Our search was based on the assumption that any machinery that senses rotational bias will be perturbed if flagellar rotation stops. We monitored the activity of the kinase in swimming cells by bioluminescence

Thomas S. Shimizu; Nicolas Delalez; Klemens Pichler; Howard C. Berg

2006-01-01

219

Proteomic analysis of Escherichia coli associated with urinary tract infections.  

PubMed

Escherichia coli is a major cause of urinary tract infections (UTIs) where the initial infection arises from bacteria originating in the bowel. However, significant differences are observed between the genomes of intestinal and urinary E. coli strains with the latter possessing many adaptations that promote growth in the urinary tract. To define further the adaptation of urinary E. coli isolates, the cellular proteomes of 41 E. coli strains, collected from cases of UTIs or random faecal samples, were compared by 2-D gel electrophoresis and principal component analysis. The data indicated that individual patients carried relatively homogenous E. coli populations, as defined by their cellular proteomes, but the populations were distinct between patients. For one patient, E. coli, isolated during two recurrent infections 3 months apart, were indistinguishable, indicating that for this patient the infections were possibly caused by the same bacterial population. To understand the basis of the discrimination of the bacteria, selected protein spots were identified by peptide fragment fingerprinting. The identified proteins were involved in a variety of metabolic and structural roles. The data obtained for these E. coli strains provide a basis from which to target key bacterial proteins for further investigation into E. coli pathogenesis. PMID:21598392

Smith, Andrew; van Rooyen, Jan-Pierre; Argo, Evelyn; Cash, Phillip

2011-06-01

220

Abundance of culturable versus viable Escherichia coli in freshwater.  

PubMed

Approved methods traditionally used for Escherichia coli enumeration in waters are culture-based. However, these methods can underestimate the E. coli abundance in aquatic systems because they do not take into account cells that remain viable but have lost the ability to grow in or on culture media. We investigated, in freshwater samples, the abundance of (i) culturable E. coli, enumerated by the most probable number microplate method and (ii) viable E. coli, estimated using a procedure called DVC-FISH, which couples fluorescent in situ hybridization (FISH) and a viability testing technique (direct viable count (DVC)). The ratio of culturable to viable E. coli was close to 1 in highly contaminated waters (samples with a high concentration of culturable E. coli), but decreased drastically for weakly contaminated samples. This indicates a large fraction of viable but nonculturable (VBNC) E. coli in the latter samples. Microcosm experiments showed that some environmental factors, such as nutrient scarcity and solar irradiation, could lead to the presence of a high proportion of VBNC E. coli. PMID:19767865

Servais, Pierre; Prats, Josué; Passerat, Julien; Garcia-Armisen, Tamara

2009-07-01

221

[Acute diarrheal disease caused by enteropathogenic Escherichia coli in Colombia].  

PubMed

Intestinal Escherichia coli pathogens are leading causes of acute diarrheal disease in children less than 5 years in Latin America, Africa and Asia and a leading cause of death in children living in poorest communities in Africa and South East Asia. Studies on the role of E. coli pathogens in childhood diarrhea in Colombia and other countries in Latin America are limited due to the lack of detection assays in clinical laboratories at the main urban medical centers. Recent studies report that enterotoxigenic E. coli is the most common E. coli pathogens associated with diarrhea in children less than 5 years of age. Other E. coli pathotypes have been detected in children with diarrhea including enteropathogenic, enteroaggregative, shiga-toxin producing and diffusely adherent E. coli. It was also found that meat and vegetables at retail stores are contaminated with Shiga-toxin producing E. coli and enteroaggregative E. coli, suggesting that food products are involved in transmission and infection of the susceptible host. More studies are necessary to evaluate the mechanisms of transmission, the impact on the epidemiology of diarrheal disease, and management strategies and prevention of these pathogens affecting the pediatric population in Colombia. PMID:25491457

Gómez-Duarte, Oscar G

2014-10-01

222

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. PMID:16151100

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

2005-01-01

223

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. PMID:9016502

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

1997-01-01

224

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. PMID:17933911

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

2007-01-01

225

The Repeatability of Adaptive Radiation During Long-Term Experimental Evolution of Escherichia coli in a  

E-print Network

The Repeatability of Adaptive Radiation During Long- Term Experimental Evolution of Escherichia radiation, we performed a selection experiment by evolving twelve independent microcosms of Escherichia coli) The Repeatability of Adaptive Radiation During Long-Term Experimental Evolution of Escherichia coli in a Multiple

Doebeli, Michael

226

Minimal Reaction Sets for Escherichia coli Metabolism under Different Growth Requirements and Uptake Environments  

E-print Network

ARTICLES Minimal Reaction Sets for Escherichia coli Metabolism under Different Growth Requirements growth rates on different substrates is introduced and applied to a flux balance model of the Escherichia and Haemophilus influenzae must be mem- bers of a minimal genome. Interestingly, only 6 out of 26 Escherichia coli

Maranas, Costas

227

Transcriptome-based determination of multiple transcription regulator activities in Escherichia coli  

E-print Network

network connectiv- ity. We used Escherichia coli carbon source transition from glucose to acetate the Escherichia coli transition from glucose to acetate media as an example. When switching from a glycolyticTranscriptome-based determination of multiple transcription regulator activities in Escherichia

Sabatti, Chiara

228

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

E-print Network

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

Morimoto, Richard

229

Resistance and virulence factors of Escherichia coli isolated from chicken.  

PubMed

Chicken meat has become an important part of the human diet and besides contamination by pathogenic Escherichia coli there is a risk of antibiotic resistance spreading via the food chain. The purpose of this study was to examine the prevalence of resistance against eight antibiotics and the presence of 14 virulence factors among 75 Escherichia coli strains isolated from chicken meat in the Czech Republic after classification into phylogenetic groups by the multiplex PCR method. More than half of strains belonged to A phylogroup, next frequently represented was B1 phylogroup, which suggests the commensal strains. The other strains were classified into phylogroups B2 and D, which had more virulence factors. Almost half of all E. coli strains were resistant to at least one of eight-tested antibiotics. A multidrug resistance was observed in 13% of strains. The most prevalent virulence genes were iucD, iss and tsh. None of genes encoding toxins was detected. Most of E. coli strains isolated from chicken meat can be considered as nonpathogenic on the basis of analysis of virulence factors, antibiotic resistance and phylogroups assignment. It can provide a useful tool for prediction of a potential risk from food contaminated by E. coli. PMID:25844863

Pavlickova, Silvie; Dolezalova, Magda; Holko, Ivan

2015-06-01

230

Recombinant protein expression in Escherichia coli: advances and challenges  

PubMed Central

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

Rosano, Germán L.; Ceccarelli, Eduardo A.

2014-01-01

231

Uncoupler Resistance in Escherichia coli: the Role of Cellular Respiration  

Microsoft Academic Search

Bioenergetic properties of a mutant strain of Escherichia coli K12 designated TUV, which is resistant to the protonophoric uncoupling agent 4,5,6,7-tetrachloro-2-trifluoromethylbenzimid- azole (TTFB) have been compared with those of its non-resistant parent, E. coli K12 Doc-S. Strain TUV grew and respired some 20-30% faster than strain Doc-S, and was cross-resistant to carbonylcyanide p-(trifluoromethoxy)phenylhydrazone and triphenyltin, but not to 2,4- dinitrophenol.

PHILIP G. QUIRK; MICHAEL R. JONES; ROBERT S. HAWORTH; R. BRIAN BEECHEY; IAIN D. CAMPBELL

1989-01-01

232

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

Microsoft Academic Search

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

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

2005-01-01

233

Soil wetting state and preferential transport of Escherichia coli in clay soils  

Microsoft Academic Search

Tallon, L. K., Si, B. C., Korber, D. and Guo, X. 2007. Soil wetting state and preferential transport of Escherichia coli in clay soils. Can. J. Soil Sci. 87: 61-72. Transport of Escherichia coli (E. coli) through soil to drinking and recreational water may pose a serious health risk. The objective of this study was to determine how initial preferred

L. K. Tallon; B. C. Si; D. Korber; X. Guo

234

Persistence of cellulitis-associated Escherichia coli DNA ngerprints in successive broiler  

E-print Network

Persistence of cellulitis-associated Escherichia coli DNA ®ngerprints in successive broiler chicken in revised form 31 March 2000; accepted 31 March 2000 Abstract Avian cellulitis in broiler chickens is primarily caused by Escherichia coli. Previous research found that the E. coli isolates of cellulitis origin

Singer, Randall

235

FRQUENCE DE ESCHERICHIA COLI ENTROPATHOGNE K99+ ST+ ET DU ROTAVIRUS DANS LES DIARRHES NONATALES  

E-print Network

FRÉQUENCE DE ESCHERICHIA COLI ENTÉROPATHOGÈNE K99+ ST+ ET DU ROTAVIRUS DANS LES DIARRHÉES variée et complexe. Les trois, agents les plus fréquemment invo- qués sont Escherichia coli died. On the first visit, rota- virus was found in faeces of 11 diarrhoeic calves and E. coli K99+ ST

Paris-Sud XI, Université de

236

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

E-print Network

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

Fernando, Chrisantha

237

Escherichia coli identification and strain discrimination using nanosecond laser-induced breakdown spectroscopy  

E-print Network

Escherichia coli identification and strain discrimination using nanosecond laser-induced breakdown April 2007 Three strains of Escherichia coli, one strain of environmental mold, and one strain and E. coli strains. This analysis showed efficient discrimination between laser-induced breakdown

Rehse, Steven J.

238

LETTER TO THE EDITOR Aminoacylated tmRNA from Escherichia coli  

E-print Network

LETTER TO THE EDITOR Aminoacylated tmRNA from Escherichia coli interacts with prokaryoticRNAs (10Sa RNAs) are unique because they function, at least in Escherichia coli, both as tRNA and mRNA (for frame coding for 9 to 27 amino acids, depending on the species+ E. coli tmRNA mediates re- cycling

Paris-Sud XI, Université de

239

Inactivation of Escherichia coli using atmospheric-pressure plasma jet  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure argon (Ar) plasma jet was applied to the inactivation of Escherichia coli. The Ar plasma jet was generated at a frequency of 10 kHz, an applied voltage of 10 kV, and an Ar gas flow rate of 10 L/min at atmospheric pressure. E. coli cells seeded on an agar medium in a Petri dish were inactivated by Ar plasma jet irradiation for 1 s. Scanning electron microscopy (SEM) revealed that E. coli cells were killed because their cell wall and membrane were disrupted. To determine the causes of the disruption of the cell wall and membrane of E. coli, we performed the following experiments: the measurement of the surface temperature of an agar medium using a thermograph, the analysis of an emission spectrum of a plasma jet obtained using a multichannel spectrometer, and the determination of the distribution of the concentration of hydrogen peroxide (H2O2) generated on an agar medium by plasma jet irradiation using semiquantitative test strips. Moreover, H2O2 solutions of different concentrations were dropped onto an agar medium seeded with E. coli cells to examine the contribution of H2O2 to the death of E. coli. The results of these experiments showed that the cell wall and membrane of E. coli were disrupted by electrons in the plasma jet, as well as by electroneutral excited nitrogen molecules (N2) and hydroxyl (OH) radicals in the periphery of the plasma jet.

Kuwahata, Hiroshi; Yamaguchi, Takeshi; Ohyama, Ryu-ichiro; Ito, Atsushi

2015-01-01

240

Acs is essential for propionate utilization in Escherichia coli.  

PubMed

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

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

2014-07-01

241

Antibodies to Escherichia coli in chronic liver diseases.  

PubMed Central

Patients with chronic active hepatitis or alcoholic cirrhosis have serum antibodies to many more serotypes of Escherichia coli than do patients with primary biliary cirrhosis or cryptogenic cirrhosis, or normal controls. They also have antibodies against more serotypes than cirrhotic patients with a portacaval shunt. These observations suggest that factors other than shunting of blood away from the liver are responsible for the increased range of antibodies. These factors are discussed. There was no correlation between the number of serotypes to which antibodies were present and the serum immunoglobulin concentration. In three patients, each with chronic active hepatitis, the antibodies were predominantly of the IgM class, while the elevation of globulin in general was mainly due to increased IgG and IgA levels. Antibodies to Escherichia coli, therefore, probably contribute only a small part of the increased globulin levels found in patients with chronic liver disease. PMID:1104410

Simjee, A E; Hamilton-Miller, J M; Thomas, H C; Brumfitt, W; Sherlock, S

1975-01-01

242

Enterotoxigenic Escherichia coli infection in captive black-footed ferrets.  

PubMed

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

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

2001-07-01

243

Enteropathogenic Escherichia coli Prevalence in Laboratory Rabbits  

PubMed Central

Rabbit-origin enteropathogenic E. coli (EPEC) causes substantial diarrhea-associated morbidity and has zoonotic potential. A culture-based survey was undertaken to ascertain its prevalence. EPEC was isolated from 6/141 (4.3%) commercially-acquired laboratory rabbits. Three of these did not have diarrhea or EPEC-typical intestinal lesions; they instead had background plasmacytic intestinal inflammation. Asymptomatically infected rabbits may function as EPEC reservoirs. PMID:23391439

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

2013-01-01

244

Development of functionalised polyelectrolyte capsules using filamentous Escherichia coli cells  

PubMed Central

Background Escherichia coli is one of the best studied microorganisms and finds multiple applications especially as tool in the heterologous production of interesting proteins of other organisms. The heterologous expression of special surface (S-) layer proteins caused the formation of extremely long E. coli cells which leave transparent tubes when they divide into single E. coli cells. Such natural structures are of high value as bio-templates for the development of bio-inorganic composites for many applications. In this study we used genetically modified filamentous Escherichia coli cells as template for the design of polyelectrolyte tubes that can be used as carrier for functional molecules or particles. Diversity of structures of biogenic materials has the potential to be used to construct inorganic or polymeric superior hybrid materials that reflect the form of the bio-template. Such bio-inspired materials are of great interest in diverse scientific fields like Biology, Chemistry and Material Science and can find application for the construction of functional materials or the bio-inspired synthesis of inorganic nanoparticles. Results Genetically modified filamentous E. coli cells were fixed in 2% glutaraldehyde and coated with alternating six layers of the polyanion polyelectrolyte poly(sodium-4styrenesulfonate) (PSS) and polycation polyelectrolyte poly(allylamine-hydrochloride) (PAH). Afterwards we dissolved the E. coli cells with 1.2% sodium hypochlorite, thus obtaining hollow polyelectrolyte tubes of 0.7 ?m in diameter and 5–50 ?m in length. For functionalisation the polyelectrolyte tubes were coated with S-layer protein polymers followed by metallisation with Pd(0) particles. These assemblies were analysed with light microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. Conclusion The thus constructed new material offers possibilities for diverse applications like novel catalysts or metal nanowires for electrical devices. The novelty of this work is the use of filamentous E. coli templates and the use of S-layer proteins in a new material construct. PMID:23259586

2012-01-01

245

Genome dynamics and its impact on evolution of Escherichia coli  

Microsoft Academic Search

The Escherichia coli genome consists of a conserved part, the so-called core genome, which encodes essential cellular functions and of a flexible,\\u000a strain-specific part. Genes that belong to the flexible genome code for factors involved in bacterial fitness and adaptation\\u000a to different environments. Adaptation includes increase in fitness and colonization capacity. Pathogenic as well as non-pathogenic\\u000a bacteria carry mobile and

Ulrich DobrindtM; M. Geddam Chowdary; G. Krumbholz; J. Hacker

2010-01-01

246

Enzymatic Replication of the Origin of the Escherichia coli Chromosome  

Microsoft Academic Search

An enzyme system that replicates plasmids bearing the origin of the Escherichia coli chromosome (oriC) has the following physiologically relevant features. The system (i) depends completely on low levels of exogenously furnished supercoiled oriC plasmids, (ii) uses only those plasmids that contain the intact oriC region of about 245 base pairs, (iii) initiates replication within or near the oriC sequence

Robert S. Fuller; Jon M. Kaguni; Arthur Kornberg

1981-01-01

247

Localization of the Tat translocon components in Escherichia coli  

Microsoft Academic Search

The Tat system has the ability to translocate folded proteins across the bacterial cytoplasmic membrane. In Escherichia coli, three functionally different translocon components have been identified, namely TatA, TatB, and TatC. These proteins were fused to the green fluorescent protein (GFP) and their localization was determined by confocal laser scanning fluorescence microscopy. TatA-GFP was distributed in the membrane, often with

Felix Berthelmann; Thomas Brüser

2004-01-01

248

Coding-Sequence Determinants of Gene Expression in Escherichia coli  

Microsoft Academic Search

Synonymous mutations do not alter the encoded protein, but they can influence gene expression. To investigate how, we engineered a synthetic library of 154 genes that varied randomly at synonymous sites, but all encoded the same green fluorescent protein (GFP). When expressed in Escherichia coli, GFP protein levels varied 250-fold across the library. GFP messenger RNA (mRNA) levels, mRNA degradation

Grzegorz Kudla; Andrew W. Murray; David Tollervey; Joshua B. Plotkin

2009-01-01

249

Activation of Escherichia coli leuV Transcription by FIS  

Microsoft Academic Search

The transcription factor FIS has been implicated in the regulation of several stable RNA promoters, including that for the major tRNALeu species in Escherichia coli, tRNA1 Leu . However, no evidence for direct involvement of FIS in tRNA1 Leu expression has been reported. We show here that FIS binds to a site upstream of the leuV promoter (centered at 271)

WILMA ROSS; JULIA SALOMON; WALTER M. HOLMES; RICHARD L. GOURSE

1999-01-01

250

Activation of glucose transport under oxidative stress in Escherichia coli  

Microsoft Academic Search

Global transcription studies have identified a large number of redox-responsive genes, although the biological relevance of\\u000a this regulation has not been experimentally tested. In particular, several genes coding for enzymes involved in glucose metabolism\\u000a have been identified as redox-responsive in Escherichia coli. However, only zwf, which codes for glucose-6-phosphate dehydrogenase, has been shown experimentally to affect the cellular resistance to

W. Rungrassamee; X. Liu; P. J. Pomposiello

2008-01-01

251

Cytoplasmic Protein Mobility in Osmotically Stressed Escherichia coli  

Microsoft Academic Search

Facile diffusion of globular proteins within a cytoplasm that is dense with biopolymers is essential to normal cellular biochemical activity and growth. Remarkably, Escherichia coli grows in minimal medium over a wide range of external osmolalities (0.03 to 1.8 osmol). The mean cytoplasmic biopolymer volume fraction () for such adapted cells ranges from 0.16 at 0.10 osmol to 0.36 at

Michael C. Konopka; Kem A. Sochacki; Benjamin P. Bratton; Irina A. Shkel; M. Thomas Record; James C. Weisshaar

2009-01-01

252

A physiology study of Escherichia coli overexpressing phosphoenolpyruvate carboxykinase.  

PubMed

To determine whether intracellular ATP levels can be affected, Escherichia coli overexpressing phosphoenolpyruvate carboxykinase (pck) or phosphoenolpyruvate carboxylase (ppc) were grown in glucose minimal medium. The Pck-overexpressing cells showed approximately twice the intracellular ATP concentration, with 22% slower growth than the Ppc-overexpressing strain. This unexpected result of higher ATP coupled with slower growth is discussed based on transcriptome analysis. PMID:18391462

Kwon, Yeong-Deok; Lee, Sang Yup; Kim, Pil

2008-04-01

253

Impact of rpoS Deletion on Escherichia coli Biofilms  

Microsoft Academic Search

Slow growth has been hypothesized to be an essential aspect of bacterial physiology within biofilms. In order to test this hypothesis, we employed two strains of Escherichia coli, ZK126 (DlacZ rpoS1) and its isogenic DrpoS derivative, ZK1000. These strains were grown at two rates (0.033 and 0.0083 h21) in a glucose-limited chemostat which was coupled either to a modified Robbins

JENNIFER L. ADAMS; ROBERT J. C. MCLEAN

1999-01-01

254

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

255

Characterization of a phosphotriesterase from genetically?engineered Escherichia coli  

Microsoft Academic Search

A phosphotriesterase (PTE) capable of hydrolyzing organophosphate esters was purified from Escherichia coli strain DH?5? carrying a cloned opd gene from Flavobacterium. The effects of pH, temperature and metal ion concentrations on enzyme stability and activity were investigated. Optimum conditions for PTE's catalytic activity were determined to be 35°C and pH 8.5. Protein?metal equilibrium binding experiments showed that PTE could

Jeffrey S. Karns; Alba Torrents

1998-01-01

256

Expression of Aeromonas caviae bla genes in Escherichia coli  

Microsoft Academic Search

An isolate of Aeromonas caviae 035 carried a 55.5 kb self-transfer able plasmid. Transfer of the plasmid to Escherichia coli K.12 resulted in the expression of a TEM-like ^-lactamase that was not expressed in parental A. caviae. The bla gene sequence was detectable by DNA hybridization and PCR amplification of the plasmid when extracted from parental A. caviae or from

Sameera Sayeed; Jon. R. Saunders; Clive Edwards; John E. Corkill; C. Anthony Hart

1996-01-01

257

Occurrence of Escherichia coli in Wild Cottontail Rabbits.  

PubMed

Free-ranging cottontail rabbits (Sylvilagus floridanus) from two areas in central Pennsylvania were sampled over a 4-year period. Large numbers of coliforms were isolated from the intestinal tracts of these animals; in 136 of the 141 rabbits sampled, Escherichia coli was found to be a major component of the alimentary flora. Four serogroups (O7, O77, O73, and O103) were predominant among the isolates and were considered resistant coliflora of this species of cottontail rabbit. PMID:16345208

Kozlowski, R; Glantz, P J; Anthony, R G

1977-03-01

258

Functional expression of an alkaline lipase in Escherichia coli  

Microsoft Academic Search

The aim of the present study was to express and evaluate a previously cloned lipase gene. In this study, the cloned gene was\\u000a subcloned in the pET15bEscherichia coli BL21(DE3) expression system. The expression of the recombinant lipase was induced using 1 mM IPTG for 3 hours. The enzyme\\u000a activity was measured using p-nitrophenyl-decanoate as substrate. The recombinant lipase showed a

Mohammed Rabbani; Hamid Mirmohammadsadeghi; Mohsen Ani; Koorosh Goodarzvand Chegini; Zahra Etemadifar; Fatemeh Moazen

2009-01-01

259

Acetic acid accumulation in aerobic growth of recombinant Escherichia coli  

Microsoft Academic Search

A correlation between ?HAc (specific acetic acid accumulation rate) and ? (specific growth rate) for a recombinant Escherichia coli BL21 strain was defined under typical conditions to achieve high cell densities (fed-batch process, dissolved oxygen concentration higher than 30% saturation, semi-synthetic medium). The feeding rate of glucose was continuously adjusted in order to support constant values of ? (0.4, 0.3,

D. C. Suárez; B. V. Kilikian

2000-01-01

260

Growth of an Escherichia coli mutant deficient in respiration  

Microsoft Academic Search

An Escherichia coli mutant deficient in genes for heme biosynthesis grew in medium of initial pH 8 containing 1% tryptone and glucose under aerobic growth conditions, and its doubling time was approximately 60 min at 37°C. The growth rate was not increased under O2-limiting conditions. When the mutant was grown in medium of initial pH 6, growth stopped at the

Lui Futatsugi; Hiromi Saito; Tomohito Kakegawa; Hiroshi Kobayashi

1997-01-01

261

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. PMID:8390819

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

1993-01-01

262

Expression of cloned monkey metallothionein in Escherichia coli.  

PubMed Central

Expression vectors were constructed in which a cDNA specifying the monkey kidney metallothionein-II (MT-II) was linked directly to the lambda PR promoter. Enhanced expression of MT-II in Escherichia coli was observed when two initiation signals were tandemly linked to the MT-II gene and the lambda cI+ host cells were induced by nalidixic acid. PMID:3103531

Murooka, Y; Nagaoka, T

1987-01-01

263

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

264

Hepatitis A virus polyprotein processing by Escherichia coli proteases  

Microsoft Academic Search

Hepatitis A virus (HAV) encodes a single polyprotein, which is post-translationally processed. This processing represents an essential step in capsid formation. The virus possesses only one protease, 3C, responsible for all cleavages, except for that at the VP1\\/2A junction region, which is processed by cellular proteases. In this study, data demonstrates that HAV polyprotein processing by Escherichia coli protease(s) leads

Rosa M. Pinto; Susana Guix; Juan F. Gonza; Santiago Caballero; Ke-Jian Guo; Enric Ribes; Albert Bosch

2002-01-01

265

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. PMID:11238988

Schaechter, Moselio

2001-01-01

266

Genome sequence of enterohaemorrhagic Escherichia coli O157:H7  

Microsoft Academic Search

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

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

2001-01-01

267

The Stringent Response and Cell Cycle Arrest in Escherichia coli  

Microsoft Academic Search

The bacterial stringent response, triggered by nutritional deprivation, causes an accumulation of the signaling nucleotides pppGpp and ppGpp. We characterize the replication arrest that occurs during the stringent response in Escherichia coli. Wild type cells undergo a RelA-dependent arrest after treatment with serine hydroxamate to contain an integer number of chromosomes and a replication origin-to-terminus ratio of 1. The growth

Daniel J. Ferullo; Susan T. Lovett

2008-01-01

268

Dynamic restacking of Escherichia Coli P-pili  

Microsoft Academic Search

P-pili of uropathogenic Escherichia coli mediate the attachment to epithelial cells in the human urinary tract and kidney and therefore play an important role in\\u000a infection. A better understanding of this mechanism could help to prevent bacteria from spreading but also provides interesting\\u000a insights into molecular mechanics for future nanotech applications. The helical rod design of P-pili provides an efficient

Robert A. Lugmaier; Staffan Schedin; Ferdinand Kühner; Martin Benoit

2008-01-01

269

Biomolecular Mechanisms of Pseudomonas aeruginosa and Escherichia coli Biofilm Formation  

PubMed Central

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

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

2014-01-01

270

Survival of Escherichia coli on strawberries grown under greenhouse conditions.  

PubMed

Strawberries are soft fruit that are not recommended to have a post-harvest wash due to quality concerns. Escherichia coli O157:H7 has been linked to outbreaks with strawberries but little is known about the survival of E. coli during the growth cycle of strawberries. The survival of E. coli on strawberry plants during growing under greenhouses conditions was evaluated. Soil, leaves, and strawberries (if present) were artificially contaminated with an E. coli surrogate either at the time of planting, first runner removal (4 wk), second runner removal (8 wk), or one week prior to harvest. At harvest E. coli was recovered from the leaves, soil, and strawberries regardless of the contamination time. Time of contamination influenced (P < 0.05) numbers of viable E. coli on the plant. The highest survival of E. coli (P < 0.0001) was detected in soil that was contaminated at planting (4.27 log10 CFU g soil(-1)), whereas, the survival of E. coli was maximal at later contamination times (8 wk and 1 wk prior to harvest) for the leaves (4.40 and 4.68 log10 CFU g leaves(-1)) and strawberries (3.37 and 3.53 log10 CFU strawberry(-1)). Cross contamination from leaves to fruit was observed during this study, with the presence of E. coli on strawberries which had not been present at the time of contamination. These results indicate that good agricultural best practices to avoid contamination are necessary to minimize the risk of contamination of these popular fruit with enteric pathogens. Practices should include soil testing prior to harvest and avoiding contamination of the leaves. PMID:25475285

Shaw, Angela Laury; Svoboda, Amanda; Jie, Beatrice; Nonnecke, Gail; Mendonca, Aubrey

2015-04-01

271

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. PMID:23275869

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

2012-01-01

272

Preharvest control of Escherichia coli O157 in cattle.  

PubMed

Bovine manure is an important source of Escherichia coli O157 contamination of the environment and foods; therefore, effective interventions targeted at reducing the prevalence and magnitude of fecal E. coli O157 excretion by live cattle (preharvest) are desirable. Preharvest intervention methods can be grouped into 3 categories: 1) exposure reduction strategies, 2) exclusion strategies, and 3) direct antipathogen strategies. Exposure reduction involves environmental management targeted at reducing bovine exposure to E. coli O157 through biosecurity and environmental niche management such as feed and drinking water hygiene, reduced exposure to insects or wildlife, and improved cleanliness of the bedding or pen floor. In the category of exclusion, we group vaccination and dietary modifications such as selection of specific feed components; feeding of prebiotics, probiotics, or both; and supplementation with competitive exclusion cultures to limit proliferation of E. coli O157 in or on exposed animals. Direct antipathogen strategies include treatment with sodium chlorate, antibiotics, bacteriophages, in addition to washing of animals before slaughter. Presently, only 1 preharvest control for E. coli O157 in cattle has been effective and has gained widespread adoption-the feeding probiotic Lactobacillus acidophilus. More research into the effectiveness of parallel and simultaneous application of 1 or more preharvest control strategies, as well as the identification of new pre-harvest control methods, may provide practical means to substantially reduce the incidence of human E. coli O157-related illness by intervening at the farm level. PMID:17145967

LeJeune, J T; Wetzel, A N

2007-03-01

273

Identification of Escherichia coli Genes Associated with Urinary Tract Infections  

PubMed Central

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

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

2012-01-01

274

Proximity-Dependent Inhibition in Escherichia coli Isolates from Cattle?  

PubMed Central

We describe a novel proximity-dependent inhibition phenotype of Escherichia coli that is expressed when strains are cocultured in defined minimal media. When cocultures of “inhibitor” and “target” strains approached a transition between logarithmic and stationary growth, target strain populations rapidly declined >4 log CFU per ml over a 2-h period. Inhibited strains were not affected by exposure to conditioned media from inhibitor and target strain cocultures or when the inhibitor and target strains were incubated in shared media but physically separated by a 0.4-?m-pore-size membrane. There was no evidence of lytic phage or extracellular bacteriocin involvement, unless the latter was only present at effective concentrations within immediate proximity of the inhibited cells. The inhibitory activity observed in this study was effective against a diversity of E. coli strains, including enterohemorrhagic E. coli serotype O157:H7, enterotoxigenic E. coli expressing F5 (K99) and F4 (K88) fimbriae, multidrug-resistant E. coli, and commensal E. coli. The decline in counts of target strains in coculture averaged 4.8 log CFU/ml (95% confidence interval, 4.0 to 5.5) compared to their monoculture counts. Coculture of two inhibitor strains showed mutual immunity to inhibition. These results suggest that proximity-dependent inhibition can be used by bacteria to gain a numerical advantage when populations are entering stationary phase, thus setting the stage for a competitive advantage when growth conditions improve. PMID:21296941

Sawant, Ashish A.; Casavant, N. Carol; Call, Douglas R.; Besser, Thomas E.

2011-01-01

275

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

PubMed

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

Qureshi, Zubair A; Doi, Yohei

2014-05-01

276

Engineering Escherichia coli K12 MG1655 to use starch  

PubMed Central

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

2014-01-01

277

Expression in Escherichia coli: becoming faster and more complex.  

PubMed

Escherichia coli is the major expression host for the production of homogeneous protein samples for structural studies. The introduction of high-throughput technologies in the last decade has further revitalized E. coli expression, with rapid assessment of different expression strategies and successful production of an ever-increasing number of proteins. In addition, miniaturization of biophysical characterizations should soon help choosing expression strategies based on quantitative and qualitative observations. Since many proteins form larger assemblies in vivo, dedicated co-expression systems for E. coli are now addressing the reconstitution of protein complexes. Yet, co-expression approaches show an increasing experimental combinatorial intricacy when considering larger complexes. The current combination of high-throughput and co-expression technologies paves the way, however, for tackling larger and more complex macromolecular assemblies. PMID:23422067

Vincentelli, Renaud; Romier, Christophe

2013-06-01

278

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. PMID:7508076

Riley, M

1993-01-01

279

Biofilm Modifies Expression of Ribonucleotide Reductase Genes in Escherichia coli  

PubMed Central

Ribonucleotide reductase (RNR) is an essential enzyme for all living organisms since is the responsible for the last step in the synthesis of the four deoxyribonucleotides (dNTPs) necessary for DNA replication and repair. In this work, we have investigated the expression of the three-RNR classes (Ia, Ib and III) during Escherichia coli biofilm formation. We show the temporal and spatial importance of class Ib and III RNRs during this process in two different E. coli wild-type strains, the commensal MG1655 and the enteropathogenic and virulent E2348/69, the prototype for the enteropathogenic E. coli (EPEC). We have established that class Ib RNR, so far considered cryptic, play and important role during biofilm formation. The implication of this RNR class under the specific growth conditions of biofilm formation is discussed. PMID:23050019

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

2012-01-01

280

Overexpression and purification of asparagine synthetase from Escherichia coli.  

PubMed

Overexpression of the asnA gene from Escherichia coli K-12 coding for asparagine synthetase (EC 6.3.1.1) was achieved with a plasmid, pUNAd37, a derivative of pUC18, in E. coli. The plasmid was constructed by optimizing a DNA sequence between the promoter and the ribosome binding region. The enzyme, comprising ca. 15% of the total soluble protein in the E. coli cell, was readily purified to apparent homogeneity by DEAE-Cellulofine and Blue-Cellulofine column chromatographies. The amino-terminal sequence, amino acid composition, and molecular weight of the purified protein agreed with the predicted values based on the DNA sequence of the gene. Furthermore the native molecular weight measured by gel filtration confirmed that asparagine synthetase exists as a dimer of identical subunits. PMID:1369484

Sugiyama, A; Kato, H; Nishioka, T; Oda, J

1992-03-01

281

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

282

???????????????????????????????????????????????????????????????? Escherichia coli ????????????????????????? ISOLATION AND SCREENING OF LACTIC ACID BACTERIA CAPABLE OF INHIBITING GROWTH OF SOME ESCHERICHIA COLI ISOLATED FROM SWINE  

Microsoft Academic Search

One hundred and forty-seven strains of lactic acid bacteria (LAB) were isolated from some soils, fermented foods, vegetables, fruits, milk and animal products. After cultivation in MRS broth at 37 ?C for 96 hours, each culture supernatant was evaluated its growth inhibitory activity by using a paper disc diffusion method against one strain of Escherichia coli O157:H7 and nine strains

Mongkhon Punyarat; Narumol Thongwai

283

EXPERIMENTAL MASTITIS WITH ESCHERICHIA COLI: SEQUENTIAL RESPONSE OF LEUKOCYTES AND OPSONIC ACTIVITY  

E-print Network

EXPERIMENTAL MASTITIS WITH ESCHERICHIA COLI: SEQUENTIAL RESPONSE OF LEUKOCYTES AND OPSONIC ACTIVITY infusion of bacteria (Hill, 1979); b) opsonic activity is required in milk to enable polymorphonuclear

Paris-Sud XI, Université de

284

Autoinducer 2-based quorum sensing response of Escherichia coli to sub-therapeutic tetracycline exposure  

E-print Network

-therapeutic tetracycline, the expression of genes associated with the conjugal transfer of antibiotic resistance plasmids, and the conjugal transfer of these plasmids in Escherichia coli. The studies showed that AI-2 activity increased in Tets E. coli in the presence...

Lu, Lingeng

2006-10-30

285

Global dissemination of a multidrug resistant Escherichia coli clone  

PubMed Central

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

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

2014-01-01

286

Proteomic analysis of uropathogenic Escherichia coli.  

PubMed

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

Cash, Phillip

2014-02-01

287

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

288

Dual infection with attaching and effacing Escherichia coli and enterotoxigenic Escherichia coli in post-weaning pigs.  

PubMed

Post-weaning diarrhoea in pigs occurred on two farms in Hokkaido, Japan, in 1994. Four piglets aged 35 or 45 days were examined after death. At necropsy, ecchymotic haemorrhages were seen on the mucosal surface of the caecum and colon. Histopathologically, numerous Gram-negative bacilli adhered to the brush border of the small intestines, but the brush border itself was intact. Typical attaching and effacing (AE) lesions were seen in the caecum and colon. Immunohistochemically, the bacilli which adhered to the brush border gave positive results with antisera against serogroup O149 of Escherichia coli; the bacilli which caused the AE lesions, however, belonged to serogroup O45. It was concluded that the disease resulted from dual infection with attaching and effacing E. coli (AEEC) and enterotoxigenic E. coli (ETEC). PMID:8729084

Wada, Y; Nakaoka, Y; Kondo, H; Nakazawa, M; Kubo, M

1996-01-01

289

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

PubMed

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

Berry, Elaine D; Wells, James E

2012-01-01

290

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

E-print Network

on biological data, none of them has examined the Escherichia coli (E. coli) gene expression data. This paper using the E. coli gene expression data, and a new evaluation method to assess them. The results show on clustering the E. coli gene expression data in order to identify unknown genes involved in the Acid Tolerance

Gruenwald, Le

291

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

E-print Network

Several methods exist for predicting non-coding RNA (ncRNA) genes in Escherichia coli (E.coli therefore speculate that E.coli contains more ncRNA genes than previously estimated. INTRODUCTION Non. We describe a method that uses automatic discovery of sequence patterns to predict ncRNA genes in E.coli

Fernandez, Thomas

292

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

293

Recent Advances in Understanding Enteric Pathogenic Escherichia coli  

PubMed Central

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

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

2013-01-01

294

Expression analysis of cloned chromosomal segments of Escherichia coli.  

PubMed Central

The novel transcription system of bacteriophage T7 was used to express Escherichia coli genes preferentially with a new low-copy-number plasmid vector, pFN476, to minimize toxic gene effects. Selected E. coli chromosomal fragments from an ordered genomic library (Y. Kohara, K. Ikiyama, and K. Isono, Cell 50:495-508, 1987) were recloned into this vector, and their genes were preferentially expressed in vivo utilizing its T7 promoter. The protein products were analyzed by two-dimensional gel electrophoresis. By using DNA sequence information, the gel migration was predicted for the protein products of open reading frames from these segments, and this information was used to identify gene products visualized as spots on two-dimensional gels. Even in the absence of DNA sequence information, this approach offers the opportunity to identify all gene products of E. coli and map their genes to within 10 kb on the E. coli genome; with sequence information, this approach can produce a definitive expression map of the E. coli genome. Images PMID:8349554

Sankar, P; Hutton, M E; VanBogelen, R A; Clark, R L; Neidhardt, F C

1993-01-01

295

Antibiotic Resistance of Escherichia coli Serotypes from Cochin Estuary  

PubMed Central

This study aimed at detecting the prevalence of antibiotic-resistant serotypes of Escherichia coli in Cochin estuary, India. E. coli strains were isolated during the period January 2010–December 2011 from five different stations set at Cochin estuary. Water samples from five different stations in Cochin estuary were collected on a monthly basis for a period of two years. Isolates were serotyped, antibiogram-phenotyped for twelve antimicrobial agents, and genotyped by polymerase chain reaction for uid gene that codes for ?-D-glucuronidase. These E. coli strains from Cochin estuary were tested against twelve antibiotics to determine the prevalence of multiple antibiotic resistance among them. The results revealed that more than 53.33% of the isolates were multiple antibiotic resistant. Thirteen isolates showed resistance to sulphonamides and two of them contained the sul 1 gene. Class 1 integrons were detected in two E. coli strains which were resistant to more than seven antibiotics. In the present study, O serotyping, antibiotic sensitivity, and polymerase chain reaction were employed with the purpose of establishing the present distribution of multiple antibiotic-resistant serotypes, associated with E. coli isolated from different parts of Cochin estuary. PMID:23008708

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

2012-01-01

296

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. PMID:16760308

Han, Mee-Jung; Lee, Sang Yup

2006-01-01

297

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. PMID:21145393

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

2011-01-01

298

Escherichia coli ST131, an intriguing clonal group.  

PubMed

In 2008, a previously unknown Escherichia coli clonal group, sequence type 131 (ST131), was identified on three continents. Today, ST131 is the predominant E. coli lineage among extraintestinal pathogenic E. coli (ExPEC) isolates worldwide. Retrospective studies have suggested that it may originally have risen to prominence as early as 2003. Unlike other classical group B2 ExPEC isolates, ST131 isolates are commonly reported to produce extended-spectrum ?-lactamases, such as CTX-M-15, and almost all are resistant to fluoroquinolones. Moreover, ST131 E. coli isolates are considered to be truly pathogenic, due to the spectrum of infections they cause in both community and hospital settings and the large number of virulence-associated genes they contain. ST131 isolates therefore seem to contradict the widely held view that high levels of antimicrobial resistance are necessarily associated with a fitness cost leading to a decrease in pathogenesis. Six years after the first description of E. coli ST131, this review outlines the principal traits of ST131 clonal group isolates, based on the growing body of published data, and highlights what is currently known and what we need to find out to provide public health authorities with better information to help combat ST131. PMID:24982321

Nicolas-Chanoine, Marie-Hélène; Bertrand, Xavier; Madec, Jean-Yves

2014-07-01

299

The Genetic Basis of Escherichia coli Pathoadaptation to Macrophages  

PubMed Central

Antagonistic interactions are likely important driving forces of the evolutionary process underlying bacterial genome complexity and diversity. We hypothesized that the ability of evolved bacteria to escape specific components of host innate immunity, such as phagocytosis and killing by macrophages (M?), is a critical trait relevant in the acquisition of bacterial virulence. Here, we used a combination of experimental evolution, phenotypic characterization, genome sequencing and mathematical modeling to address how fast, and through how many adaptive steps, a commensal Escherichia coli (E. coli) acquire this virulence trait. We show that when maintained in vitro under the selective pressure of host M? commensal E. coli can evolve, in less than 500 generations, virulent clones that escape phagocytosis and M? killing in vitro, while increasing their pathogenicity in vivo, as assessed in mice. This pathoadaptive process is driven by a mechanism involving the insertion of a single transposable element into the promoter region of the E. coli yrfF gene. Moreover, transposition of the IS186 element into the promoter of Lon gene, encoding an ATP-dependent serine protease, is likely to accelerate this pathoadaptive process. Competition between clones carrying distinct beneficial mutations dominates the dynamics of the pathoadaptive process, as suggested from a mathematical model, which reproduces the observed experimental dynamics of E. coli evolution towards virulence. In conclusion, we reveal a molecular mechanism explaining how a specific component of host innate immunity can modulate microbial evolution towards pathogenicity. PMID:24348252

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

2013-01-01

300

GENETIC CONTROL OF RESTRICTION AND MODIFICATION IN ESCHERICHIA COLI1  

PubMed Central

Boyer, Herbert (Yale University, New Haven, Conn.). Genetic control of restriction and modification in Escherichia coli. J. Bacteriol. 88:1652–1660. 1964.—Bacterial crosses with K-12 strains of Escherichia coli as Hfr donors (Hfr Hayes, Hfr Cavalli, and Hfr P4X-6) and B/r strains of E. coli as F? recipients were found to differ from crosses between K-12 Hfr donors and K-12 F? recipients in two ways: (i) recombinants (leu, pro, lac, and gal) did not appear at discrete time intervals but did appear simultaneously 30 min after matings were initiated, and (ii) the linkage of unselected markers to selected markers was reduced. Integration of a genetic region linked to the threonine locus of K-12 into the B/r genome resulted in a hybrid which no longer gave anomalous results in conjugation experiments. A similar region of the B strain was introduced into the K-12 strain, which then behaved as a typical B F? recipient. These observations are interpreted as the manifestation of host-controlled modification and restriction on the E. coli chromosome. This was verified by experiments on the restriction and modification of the bacteriophage lambda, F-lac, F-gal, and sex-factor, F1. It was found that the genetic region that controlled the mating responses of the K-12 and B/r strains also controlled the modification and restriction properties of these two strains. The genes responsible for the restricting and modifying properties of the K-12 and B strains of E. coli were found to be allelic, linked to each other, and linked to the threonine locus. PMID:14240953

Boyer, Herbert

1964-01-01

301

Effects of exogenous nutrients on polyketide biosynthesis in Escherichia coli.  

PubMed

Heterologous hosts are important platforms for engineering natural product biosynthesis. Escherichia coli is such a host widely used for expression of various biosynthetic enzymes. While numerous studies have been focused on optimizing the expression conditions for desired functional proteins, this work describes how supplement of exogenous nutrients into the fermentation broth influences the formation of natural products in E. coli. A type III polyketide synthase gene stts from Streptomyces toxytricini NRRL 15443 was heterogeneously expressed in E. coli BL21(DE3). This enzyme uses five units of malonyl-CoA to generate a polyketide 1,3,6,8-tetrahydroxynaphthalene, which can be spontaneously oxidized into a red compound flaviolin. In this work, we manipulated the fermentation broth of E. coli BL21(DE3)/pET28a-stts by supplying different nutrients including glucose and sodium pyruvate at different concentrations, from which six flaviolin derivatives 1-6 were produced. While addition of glucose yielded the production of 1-4, supplement of sodium pyruvate into the induced broth of E. coli BL21(DE3)/pET28a-stts resulted in the synthesis of 5 and 6, suggesting that different nutrients may enable E. coli to generate different metabolites. These products were purified and structurally characterized based on the spectral data, among which 2-6 are novel compounds. These molecules were formed through addition of different moieties such as acetone and indole to the flaviolin scaffold. The concentrations of glucose and sodium pyruvate and incubation time affect the product profiles. This work demonstrates that supplement of nutrients can link certain intracellular metabolites to the engineered biosynthetic pathway to yield new products. It provides a new approach to biosynthesizing novel molecules in the commonly used heterologous host E. coli. PMID:25411046

Sun, Lei; Zeng, Jia; Zhang, Shuwei; Gladwin, Tyler; Zhan, Jixun

2015-01-01

302

Transport of purines and deoxyadenosine in Escherichia coli.  

PubMed

The characteristics of adenine, guanine, hypoxanthine, xanthine, and uracil uptake in Escherichia coli B show that each base is transported by a specific system. The data support the concept that the transport of guanine, hypoxanthine, xanthine, and uracil function without direct involvement of the respective purine or pyrimidine phosphoribosyltransferase enzymes. Uracil phosphoribosyltransferase is not demonstrable in E. coli B, and large differences are observed in the inhibitory effects of heterologous purines on the uptake of guanine, hypoxanthine, and xanthine as compared to the corresponding inhibitory effects reported for the soluble purine phosphoribosyltransferase enzymes of E. coli B. Additional evidence is provided by the low Km values determined for the transport of adenine, guanine, hypoxanthine, and xanthine relative to the corresponding Km values for the phosphoribosyltransferase enzymes. Data are presented indicating that adenine may be transported without participation of adenine phosphoribosyltransferase. The stimulatory effect of glucose, the inhibitory effect of KCN, and the high intracellular to extracellular concentration gradients of the bases produced in the presence of glucose provide evidence that the transport processes are energy-dependent. The Km values for transport of the purines and uracil range from 10(-7) M to 5 X 10(-7) M. Characteristics of adenine and uracil uptake are similar in E. coli B, E. coli K-12, and a showdomycin-resistant mutant of E. coli B. Adenosine and deoxyadenosine are transported in E. coli B by independent transport systems. Adenine or hypoxanthine does not share the adenosine or deoxyadenosine transport systems as evidence by the mutual lack of competition of free bases and nucleosides on transport. The transport systems for deoxyadenosine and adenosine are defective in the mutant. PMID:1104620

Roy-Burman, S; Visser, D W

1975-12-25

303

Contamination of beef chucks with Escherichia coli during carcass breaking.  

PubMed

Samples were obtained by swabbing the whole of the chuck portion on each of the first 500 sides that entered a beef carcass breaking process and the whole of the outer surface of each of the chuck primal cuts that were prepared from those portions. Swabs obtained from groups of 10 sides or cuts that entered or emerged from the process consecutively were combined, and the coliforms and Escherichia coli recovered from each group were enumerated. Coliforms and E. coli were recovered only sporadically from groups of sides at log total numbers of 4.0 and 3.5 log CFU/500 sides, respectively. Coliforms were recovered from three and E. coli from none of the first six groups of cuts. Coliforms and E. coli were recovered from all subsequent groups of cuts, initially at log numbers mostly <3 log CFU/10 cuts, but ultimately at log numbers mostly >3 log CFU/10 cuts. The log total numbers of coliforms and E. coli recovered from cuts were >6.0 and 5.5 log CFU/500 cuts, respectively. After the breaking of about 600 sides, samples were obtained by swabbing a table onto which the part of the side that included the chuck portion was deposited after it was cut from the hanging side, and the belt that was used for conveying chucks. The numbers of coliforms and E. coli recovered from the table and conveyor belt were comparable with the numbers recovered from sides and cuts, respectively. Those findings show that most of the coliforms and E. coli recovered from the cuts were not present on carcass sides but that they originated largely from the cut conveying equipment. PMID:11726167

Gill, C O; McGinnis, J C; Bryant, J

2001-11-01

304

Glucosylation of Isoflavonoids in Engineered Escherichia coli  

PubMed Central

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

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

2014-01-01

305

Persistent Colonization of Sheep by Escherichia coli O157:H7 and Other E. coli Pathotypes  

PubMed Central

Shiga toxin-producing Escherichia coli (STEC) is an important cause of food-borne illness in humans. Ruminants appear to be more frequently colonized by STEC than are other animals, but the reason(s) for this is unknown. We compared the frequency, magnitude, duration, and transmissibility of colonization of sheep by E. coli O157:H7 to that by other pathotypes of E. coli. Young adult sheep were simultaneously inoculated with a cocktail consisting of two strains of E. coli O157:H7, two strains of enterotoxigenic E. coli (ETEC), and one strain of enteropathogenic E. coli. Both STEC strains and ETEC 2041 were given at either 107 or 1010 CFU/strain/animal. The other strains were given only at 1010 CFU/strain. We found no consistent differences among pathotypes in the frequency, magnitude, and transmissibility of colonization. However, the STEC strains tended to persist to 2 weeks and 2 months postinoculation more frequently than did the other pathotypes. The tendency for persistence of the STEC strains was apparent following an inoculation dose of either 107 or 1010 CFU. One of the ETEC strains also persisted when inoculated at 1010 CFU. However, in contrast to the STEC strains, it did not persist when inoculated at 107 CFU. These results support the hypothesis that STEC is better adapted to persist in the alimentary tracts of sheep than are other pathotypes of E. coli. PMID:11055945

Cornick, N. A.; Booher, S. L.; Casey, T. A.; Moon, H. W.

2000-01-01

306

MinD and MinE Interact with Anionic Phospholipids and Regulate Division Plane Formation in Escherichia coli*S  

E-print Network

in Escherichia coli*S Received for publication,August 3, 2012, and in revised form, September 22, 2012 Published machinery in Escherichia coli cells. Previous studies identified that interactions of Min, kinetics, and ATPase activity of E. coli MinD, MinE, and MinDE binding to supported lipid bilayers

Weibel, Douglas B.

307

Escherichia coli O 157: outbreak in a day nursery.  

PubMed

Seventeen out of 54 preschool children at a day nursery became infected with Escherichia coli O 157. The nursery outbreak formed part of a wider community outbreak, whose source was not identified. Epidemiological investigation suggested that the nursery outbreak resulted from person to person spread. Children with diarrhoea or a positive faecal specimen were excluded until their symptoms had resolved and one negative faecal specimen had been obtained. Children who were asymptomatic throughout were not excluded. This policy appeared to be effective in preventing further spread of infection within the nursery. PMID:7531569

Allaby, M A; Mayon-White, R

1995-01-01

308

Characterization of Pyridoxine Auxotrophs of Escherichia coli: P1 Transduction  

PubMed Central

Pyridoxine mutants of Escherichia coli B, previously divided into a minimum of six groups by cross-feeding tests, were characterized by transduction studies performed with phage P1bt. The results of these studies allowed division of pyridoxine mutants into five unlinked groups and set the minimum number of enzymes between pyridoxal phosphate and a metabolite common to other pathways at six or seven, with the probable maximum at ten. One group was shown to be linked to thr, leu, and pyrA. PMID:4887517

Dempsey, Walter B.

1969-01-01

309

Construction, expression, and characterization of recombinant hirudin in Escherichia coli.  

PubMed

The mutant gene of HV2-K47 was obtained by polymerase chain reaction-directed mutagenesis and expressed in Escherichia coli. Many elements that could affect its expression level were compared. The product was purified to homogeneity via three chromatographic steps--ion exchange, gel filtration, and reverse phase chromatography--on the AKTA Explorer System. The anti-thrombin activity of HV2-K47 is much higher than that of recombinant HV2. Some properties and expression conditions were investigated systematically, which would be useful for further studies of hirudin and other small proteins. PMID:11665804

Bi, Q; Zhang, J; Huang, Y; Su, H; Zhou, X; Zhu, S

2001-07-01

310

Escherichia coli RNA polymerase core and holoenzyme structures  

PubMed Central

Multisubunit RNA polymerase is an essential enzyme for regulated gene expression. Here we report two Escherichia coli RNA polymerase structures: an 11.0 ? structure of the core RNA polymerase and a 9.5 ? structure of the ?70 holoenzyme. Both structures were obtained by cryo-electron microscopy and angular reconstitution. Core RNA polymerase exists in an open conformation. Extensive conformational changes occur between the core and the holoenzyme forms of the RNA polymerase, which are largely associated with movements in ??. All common RNA polymerase subunits (?2, ?, ??) could be localized in both structures, thus suggesting the position of ?70 in the holoenzyme. PMID:11118218

Finn, Robert D.; Orlova, Elena V.; Gowen, Brent; Buck, Martin; van Heel, Marin

2000-01-01

311

Metal ion content of Escherichia coli versus cell age.  

PubMed Central

The potassium, calcium, magnesium, and zinc ion content of cells in exponential and synchronously growing cultures of Escherichia coli B/r was determined with an X-ray fluorescence spectrometer and an atomic absorption spectrophotometer. Cellular potassium, calcium, and magnesium content increased smoothly during the cell cycle, but cellular zinc showed a steplike increase about 10 to 15 min after cell division in a culture having a doubling time of 47 min. The possible role of cellular zinc in the control of cell division is discussed. PMID:780340

Kung, F C; Raymond, J; Glaser, D A

1976-01-01

312

Multiple defects in Escherichia coli mutants lacking HU protein.  

PubMed Central

The HU protein isolated from Escherichia coli, composed of two partially homologous subunits, alpha and beta, shares some of the properties of eucaryotic histones and is a major constituent of the bacterial nucleoid. We report here the construction of double mutants totally lacking both subunits of HU protein. These mutants exhibited poor growth and a perturbation of cell division, resulting in the formation of anucleate cells. In the absence of HU, phage Mu was unable to grow, to lysogenize, or to carry out transposition. Images PMID:2544551

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

1989-01-01

313

Adherence of enteropathogenic Escherichia coli to intestinal epithelium in vivo.  

PubMed Central

Two porcine strains of enteropathogenic Escherichia coli, one possessing K88 antigen and one lacking K88, were orally inoculated into conventional neonatal piglets. Athough both strains caused severe diarrhea, only the K88-possessing strain was able to proliferate in the anterior small intestine. Both K88-possessing and K88-lacking strains were found in large numbers in the posterior small intestine and, using fluorescent antibodies and scanning and transmission electron microscopy, were found adhering to the epitheial surface in these regions. The presence of an unusual surface structure on the bacterial cell of the K88-lacking strain was described. Images PMID:1104479

Hohmann, A; Wilson, M R

1975-01-01

314

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. PMID:3892488

Zurawski, G; Zurawski, S M

1985-01-01

315

Escherichia coli response to exogenous pyrophosphate and analogs.  

PubMed

The addition of exogenous pyrophosphate increases the growth yield and cAMP synthesis in stationary phase when Escherichia coli is grown in minimal medium. Pyrophosphate increases the yield by altering the enterobactin uptake system. We studied the physiological effects and examined how the E. coli transcriptome was modified when two structural analogs of pyrophosphate were added to the growth medium. Methylenediphosphonic acid or a high concentration of iron had the same positive effects as pyrophosphate on growth yield, cAMP synthesis and the repression of Fur-regulated genes. In contrast, imidodiphosphate did not affect these cellular processes significantly. The transcriptome modifications generated by pyrophosphate or methylenediphosphonic acid were more similar than those generated by imidodiphosphate or excess iron. The transcriptome data also indicated that processes other than iron uptake might be involved in the cellular response to exogenous pyrophosphate or methylenediphosphonic acid. PMID:12673060

Biville, Francis; Oshima, Taku; Mori, Hirotada; Kawagoe, Yuya; Bouvet, Odile; Rager, Marie-Noëlle; Perrotte-Piquemal, Marina; Danchin, Antoine

2003-01-01

316

Engineering of NADPH regenerators in Escherichia coli for enhanced biotransformation.  

PubMed

Efficient regeneration of NADPH is one of the limiting factors that constrain the productivity of biotransformation processes. In order to increase the availability of NADPH for enhanced biotransformation by engineered Escherichia coli, modulation of the pentose phosphate pathway and amplification of the transhydrogenases system have been conventionally attempted as primary solutions. Recently, other approaches for stimulating NADPH regeneration during glycolysis, such as replacement of native glyceradehdye-3-phosphate dehydrogenase (GAPDH) with NADP-dependent GAPDH from Clostridium acetobutylicum and introduction of NADH kinase catalyzing direct phosphorylation of NADH to NADPH from Saccharomyces cerevisiae, were attempted and resulted in remarkable impacts on NADPH-dependent bioprocesses. This review summarizes several metabolic engineering approaches used for improving the NADPH regenerating capacity in engineered E. coli for whole-cell-based bioprocesses and discusses the key features and progress of those attempts. PMID:23420268

Lee, Won-Heong; Kim, Myoung-Dong; Jin, Yong-Su; Seo, Jin-Ho

2013-04-01

317

Density gradient enrichment of Escherichia coli lpxL mutants.  

PubMed

We previously described enrichment of conditional Escherichia coli msbA mutants defective in lipopolysaccharide export using Ludox density gradients (Doerrler WT (2007) Appl Environ Microbiol 73; 7992-7996). Here, we use this approach to isolate and characterize temperature-sensitive lpxL mutants. LpxL is a late acyltransferase of the pathway of lipid A biosynthesis (The Raetz Pathway). Sequencing the lpxL gene from the mutants revealed the presence of both missense and nonsense mutations. The missense mutations include several in close proximity to the enzyme's active site or conserved residues (E137K, H132Y, G168D). These data demonstrate that Ludox gradients can be used to efficiently isolate conditional E. coli mutants with defects in lipopolysaccharide biosynthesis and provide insight into the enzymatic mechanism of LpxL. PMID:22554681

Six, David A; Lambert, Bliss; Raetz, Christian R H; Doerrler, William T

2012-07-01

318

Global Analysis of Extracytoplasmic Stress Signaling in Escherichia coli  

PubMed Central

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

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

2009-01-01

319

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

320

Nanomechanical motion of Escherichia coli adhered to a surface  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

321

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

322

Splenic abscess: Plasmodium vivax with secondary Escherichia coli infection.  

PubMed

Splenic abscess is a rare clinical entity as described in literature. The incidence is in the range of 0.14-0.7% and it has a high mortality rate. Hence, it is important to know its clinical presentation and complications, so that it can be treated early. We report a 40-year-old diabetic man who presented with fever with chills and rigor for the last 9 days and heaviness in the left hypochondrium for the last 6 days. He was initially diagnosed as having splenomegaly due to Plasmodium vivax (P. vivax), but was later found to have a splenic abscess due to Escherichia coli (E. coli). This was successfully managed by catheter drainage (CD) and antibiotic treatment. PMID:25505193

Tomar, Laxmikant Ramkumarsingh; Rajendran, Ranjith; Pandey, Santosh Kumar; Aggarwal, Amitesh

2015-04-01

323

Nanomechanical motion of Escherichia coli adhered to a surface.  

PubMed

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

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

2014-09-15

324

Examining the feasibility of bulk commodity production in Escherichia coli.  

PubMed

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

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

2012-04-01

325

Expression of the Escherichia coli lacZ Gene on a Plasmid Vector in a Cyanobacterium  

Microsoft Academic Search

A biphasic plasmid vector was used to introduce the Escherichia coli K-12 lac operon into the unicellular cyanobacterium Agmenellum quadruplicatum PR-6. The PR-6 transformants expressed beta -galactosidase at nearly as high a level as did Escherichia coli transformants. In order to accomplish this, it was necessary to obtain PR-6 mutants that could be transformed by plasmids with unmodified recognition sites

Jeffrey S. Buzby; Ronald D. Porter; S. Edward Stevens

1985-01-01

326

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

E-print Network

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

Dunlop, Mary

327

Review article Escherichia coli as a pathogen in dogs and cats  

E-print Network

Review article Escherichia coli as a pathogen in dogs and cats Lothar Beutin Robert Koch; accepted 17December 1998) Abstraet-Certain strains of Escherichia coli behave as pathogens in dogs and cats were clearly associated with enteric disease in young dogs. ETEC isolates from diar- rhoeic dogs were

Paris-Sud XI, Université de

328

Specificity of a Monoclonal Antibody for Alkaline Phosphatase in Escherichia coli and Shigella Species  

Microsoft Academic Search

The specificity of monoclonal antibody 2E5 for the alkaline phosphatase of Escherichia coli was studied against the alkaline phosphatases of 251 other bacterial strains. The organisms used included members of the six species of the genus Escherichia (E. coli, E. fergusonii, E. hermannii, E. blattae, E. vulneris, E. adecarboxylata), 41 species representing the family Enterobacteriaceae, and, in addition, Pseudomonas aeruginosa,

P. A. TRINELY; C. MIELCAREK; F. GAVINI; C. CARON; D. IZARD

329

Variation of the folding and dynamics of the Escherichia coli chromosome with growth conditions  

E-print Network

Variation of the folding and dynamics of the Escherichia coli chromosome with growth conditions Biosciences, Northwestern University, Evanston, IL 60208, USA. Summary We examine whether the Escherichia coli an inducible GFP fusion to the nucleoid-associated protein Fis to non- specifically decorate the entire

Kowalczykowski, Stephen C.

330

760 Biochemical Society Transactions (2007) Volume 35, part 4 Neurotensin receptor type 1: Escherichia coli  

E-print Network

: Escherichia coli expression, purification, characterization and biophysical study P.J. Harding*, H. Attrill and purified in an active form. To this end, rat NTS1 has been expressed in Escherichia coli in an active resonance. Abbreviations used: CFP, cyan fluorescent protein; GFP, green fluorescent protein; GPCR, G

Watts, Anthony

2007-01-01

331

Cell cycle analysis of plasmid-containing Escherichia coli HB 101 populations with flow cytometry  

Microsoft Academic Search

The relationship between cell mass and cell number dynamics for bacteria such as Escherichia coli depends on the cell cycle parameters C and D. Effects of plasmid copy number on these cell cycle parameters have been studied for Escherichia coli HB101 containing pMB1 plasmids propagated at different copy numbers ranging from 12 to 122. Determination of cell cycle and cell

J. H. Seo; J. E. Bailey

1987-01-01

332

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

E-print Network

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

Zulfiqar Ahmad

333

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),...

334

Antibiotics Susceptibility Pattern of Escherichia coli Strains Isolated from Chickens with Colisepticemia in Tabriz Province, Iran  

Microsoft Academic Search

Antimicrobial agents are used extremely in order to reducing the enormous losses caused by Escherichia coli infections (colibacillosis) in Iran poultry industry. In this investigation fifty avian pathogenic Escherichia coli (APEC) strains isolated from broiler chickens with colisepticemia and examined for susceptibility to antimicrobials of veterinary and human significance. In vitro antibiotic activities of 3 2 antibiotic substances against the

2006-01-01

335

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

336

Genomic transcriptional response to loss of chromosomal supercoiling in Escherichia coli  

Microsoft Academic Search

BACKGROUND: The chromosome of Escherichia coli is maintained in a negatively supercoiled state, and supercoiling levels are affected by growth phase and a variety of environmental stimuli. In turn, supercoiling influences local DNA structure and can affect gene expression. We used microarrays representing nearly the entire genome of Escherichia coli MG1655 to examine the dynamics of chromosome structure. RESULTS: We

Brian J Peter; Javier Arsuaga; Adam M Breier; Arkady B Khodursky; Patrick O Brown; Nicholas R Cozzarelli

2004-01-01

337

Domain Organization of Escherichia coli Transcript Cleavage Factors GreA and GreB*  

E-print Network

Domain Organization of Escherichia coli Transcript Cleavage Factors GreA and GreB* (Received University, New York, New York 10021 The GreA and GreB proteins of Escherichia coli in- duce cleavage activity and the GreA or GreB specificity of transcript cleavage is determined by the N-terminal domain

Sali, Andrej

338

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

PubMed Central

Genomic DNA from Streptococcus equisimilis strain H46A was cloned in Escherichia coli by using the bacteriophage lambda replacement vector L47 and an in vitro packaging system. A casein/plasminogen overlay technique was used to screen the phage bank for recombinants carrying the streptokinase gene ( skc ). The gene was present with a frequency of 1 in 836 recombinants, and 10 independent clones containing skc were isolated and physically characterized. One recombinant clone was used to subclone skc in E. coli plasmid vectors. Plasmid pMF2 [10.4 kilobases (kb)] consisting of pACYC184 with a 6.4-kb H46A DNA fragment in the EcoRI site and pMF5 (6.9 kb) carrying a 2.5-kb fragment in the Pst I site of pBR322 were among the recombinant plasmids determining streptokinase production in three different E. coli host strains. Expression of skc was independent of its orientation in either vector, indicating that its own promoter was present and functional in E. coli. However, expression in pBR322 was more efficient in one orientation than in the other, suggesting that one or both of the bla gene promoters contributed to skc expression. Several lines of evidence, including proof obtained by the immunodiffusion technique, established the identity of E. coli streptokinase. Testing cell-free culture supernatant fluids, osmotic shock fluids, and sonicates of osmotically shocked cells for streptokinase activity revealed the substance to be present in all three principal locations, indicating that E. coli cells were capable of releasing substantial amounts of streptokinase into the culture medium. Images PMID:6374659

Malke, H; Ferretti, J J

1984-01-01

339

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. PMID:20624226

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

2010-01-01

340

Demonstration of exopolysaccharide production by enterohemorrhagic Escherichia coli.  

PubMed

Enterohemorrhagic Escherichia coli O157:H7 produces visibly slimy colonies when grown on Sorbitol/MacConkey or Maloney's agar plates at room temperature, indicative of exopolysaccharide (EPS) production. Eighteen of 27 (67%) wild-type E. coli O157:H7 isolates produced enough EPS to be visually distinguishable. Of five strains that showed no visible EPS production on these media, four (80%) did produce slimy colonies on media containing higher salt concentrations. Measurements of EPS production by colorimetric determination of uronic acid indicated that EPS production was affected by growth temperature, atmosphere, and medium. Wild-type E. coli O157:H7 strain 932 produced the greatest amounts of EPS when grown anaerobically at 37 degrees C, whereas its plasmid-cured derivative 932P produced large quantities of EPS when grown aerobically at room temperature. Electron micrographs revealed thin, flexible fibers extending from the bacterial cell surface. Cells of strain 932P grown aerobically at room temperature were completely encased in a thick EPS matrix. Chemical analysis of purified EPS revealed that it is very similar or identical to colanic acid. E. coli O157:H7 adheres better to INT 407 cells when grown under conditions that favor high EPS production than when grown under conditions that repress EPS production. PMID:1369498

Junkins, A D; Doyle, M P

1992-07-01

341

L-tyrosine production by deregulated strains of Escherichia coli.  

PubMed

The excretion of the aromatic amino acid L: -tyrosine was achieved by manipulating three gene targets in the wild-type Escherichia coli K12: The feedback-inhibition-resistant (fbr) derivatives of aroG and tyrA were expressed on a low-copy-number vector, and the TyrR-mediated regulation of the aromatic amino acid biosynthesis was eliminated by deleting the tyrR gene. The generation of this L: -tyrosine producer, strain T1, was based only on the deregulation of the aromatic amino acid biosynthesis pathway, but no structural genes in the genome were affected. A second tyrosine over-producing strain, E. coli T2, was generated considering the possible limitation of precursor substrates. To enhance the availability of the two precursor substrates phosphoenolpyruvate and erythrose-4-phosphate, the ppsA and the tktA genes were over-expressed in the strain T1 background, increasing L: -tyrosine production by 80% in 50-ml batch cultures. Fed-batch fermentations revealed that L: -tyrosine production was tightly correlated with cell growth, exhibiting the maximum productivity at the end of the exponential growth phase. The final L: -tyrosine concentrations were 3.8 g/l for E. coli T1 and 9.7 g/l for E. coli T2 with a yield of L: -tyrosine per glucose of 0.037 g/g (T1) and 0.102 g/g (T2), respectively. PMID:17221195

Lütke-Eversloh, Tina; Stephanopoulos, Gregory

2007-05-01

342

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. PMID:9226257

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

1997-01-01

343

Direct cadaverine production from cellobiose using ?-glucosidase displaying Escherichia coli  

PubMed Central

In this study, we demonstrate the one-step production of cadaverine (1,5-diaminopentane) from cellobiose using an Escherichia coli strain displaying ?-glucosidase (BGL) on its cell surface. L-lysine decarboxylase (CadA) derived from E. coli and BGL from Thermobifida fusca YX (Tfu0937) fused to the anchor protein Blc from E. coli were co-expressed using E. coli as a host. The expression of CadA was confirmed by Western blotting and BGL activity on the cell surface was evaluated using pNPG as a substrate. Growth on cellobiose as the sole carbon source was also achieved. The OD600 value of the BGL and CadA co-expressing strain was 8.0 after 48 h cultivation, which is higher than that obtained by growth on glucose (5.4 after 48 h cultivation). The engineered strain produced cadaverine from cellobiose more effectively than from glucose: 6.1 mM after 48 h from 28 g/L of consumed cellobiose, vs. 3.3 mM from 20 g/L of consumed glucose. PMID:24206923

2013-01-01

344

Dynamic transcriptional response of Escherichia coli to inclusion body formation.  

PubMed

Escherichia coli is used intensively for recombinant protein production, but one key challenge with recombinant E. coli is the tendency of recombinant proteins to misfold and aggregate into insoluble inclusion bodies (IBs). IBs contain high concentrations of inactive recombinant protein that require recovery steps to salvage a functional recombinant protein. Currently, no universally effective method exists to prevent IB formation in recombinant E. coli. In this study, DNA microarrays were used to compare the E. coli gene expression response dynamics to soluble and insoluble recombinant protein production. As expected and previously reported, the classical heat-shock genes had increased expression due to IB formation, including protein folding chaperones and proteases. Gene expression levels for protein synthesis-related and energy-synthesis pathways were also increased. Many transmembrane transporter and corresponding catabolic pathways genes had decreased expression for substrates not present in the culture medium. Additionally, putative genes represented over one-third of the genes identified to have significant expression changes due to IB formation, indicating many important cellular responses to IB formation still need to be characterized. Interestingly, cells grown in 3% ethanol had significantly reduced gene expression responses due to IB formation. Taken together, these results indicate that IB formation is complex, stimulates the heat-shock response, increases protein and energy synthesis needs, and streamlines transport and catabolic processes, while ethanol diminished all of these responses. PMID:24338599

Baig, Faraz; Fernando, Lawrence P; Salazar, Mary Alice; Powell, Rhonda R; Bruce, Terri F; Harcum, Sarah W

2014-05-01

345

Modeling Escherichia coli removal in constructed wetlands under pulse loading.  

PubMed

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

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

2014-03-01

346

Characterization of murine monoclonal antibodies to Escherichia coli J5.  

PubMed Central

Twenty-eight independently derived monoclonal antibodies (MAb) directed against Escherichia coli J5 endotoxin were produced and characterized. Each MAb exhibited a specific titer by both radioimmunoassay and passive hemagglutination assay. Most of the MAb were of the immunoglobulin G isotype; however, several immunoglobulin M antibodies and one immunoglobulin A antibody were produced. When characterized for their capacity to cross-react with purified endotoxin preparations from several gram-negative bacteria, 22 MAb exhibited no cross-reactivity; 6 demonstrated a limited capacity to cross-react with other endotoxin preparations. When characterized for their capacity to react with the intact organism instead of the purified endotoxin the pattern of cross-reactivity was quite different. Most of the MAb were able to react with Salmonella minnesota Re595. Eighteen were able to react with E. coli O111:B4 (the parent strain of E. coli J5), 13 MAb reacted weakly with Pseudomonas aeruginosa, and 3 reacted weakly with Klebsiella pneumonia. The data imply that MAb generated against E. coli J5 endotoxin demonstrate greater cross-reactivity when assayed against the whole bacterium than when assayed against the corresponding purified endotoxin. We were unable to demonstrate that any of the 28 MAb could passively protect mice against lethal endotoxin challenge. PMID:3514463

Miner, K M; Manyak, C L; Williams, E; Jackson, J; Jewell, M; Gammon, M T; Ehrenfreund, C; Hayes, E; Callahan, L T; Zweerink, H

1986-01-01

347

CRISPR-Cas Functional Module Exchange in Escherichia coli  

PubMed Central

ABSTRACT Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (cas) genes constitute the CRISPR-Cas systems found in the Bacteria and Archaea domains. At least in some strains they provide an efficient barrier against transmissible genetic elements such as plasmids and viruses. Two CRISPR-Cas systems have been identified in Escherichia coli, pertaining to subtypes I-E (cas-E genes) and I-F (cas-F genes), respectively. In order to unveil the evolutionary dynamics of such systems, we analyzed the sequence variations in the CRISPR-Cas loci of a collection of 131 E. coli strains. Our results show that the strain grouping inferred from these CRISPR data slightly differs from the phylogeny of the species, suggesting the occurrence of recombinational events between CRISPR arrays. Moreover, we determined that the primary cas-E genes of E. coli were altogether replaced with a substantially different variant in a minor group of strains that include K-12. Insertion elements play an important role in this variability. This result underlines the interchange capacity of CRISPR-Cas constituents and hints that at least some functional aspects documented for the K-12 system may not apply to the vast majority of E. coli strains. PMID:24473126

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

2014-01-01

348

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

349

Inefficient replication reduces RecA-mediated repair of UV-damaged plasmids introduced into competent Escherichia coli  

E-print Network

into competent Escherichia coli H.A. Jeiranian , C.T. Courcelle, J. Courcelle Department of Biology, Portland Keywords: Transformation Escherichia coli Nucleotide excision repair recA recF recBC a b s t r a c t Transformation of Escherichia coli with purified plasmids containing DNA damage is fre- quently used as a tool

Courcelle, Justin

350

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

E-print Network

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

Meir, Yigal

351

Opposite effects of cefoperazone and ceftazidime on S-ribosylhomocysteine lyase/autoinducer-2 quorum sensing and biofilm formation by an Escherichia coli clinical isolate  

PubMed Central

To investigate the effects of subminimum inhibitory concentrations of cephalosporins on bacterial biofilm formation, the biofilm production of 52 Escherichia (E.) coli strains was examined following treatment with cephalosporin compounds at 1/4 minimum inhibitory concentrations (MICs). Ceftazidime (CAZ) inhibited biofilm formation in seven isolates, while cefoperazone (CFP) enhanced biofilm formation in 18 isolates. Biofilm formation of E. coli E42 was inhibited by CAZ and induced by CFP. Therefore, using reverse transcription-polymerase chain reaction, the expression of the biofilm-modulating genes of this isolate was investigated. To monitor the production of the autoinducer of quorum sensing in E. coli, autoinducer-2 (AI-2) production was detected by measuring the bioluminescence response of Vibrio harveyi BB170. Antisense oligonucleotides (AS-ODNs) targeting S-ribosylhomocysteine lyase (luxS) inhibited the expression of the luxS gene in E. coli. CAZ at 1/4 MIC reduced luxS mRNA levels and the production of AI-2, whereas CFP at 1/4 MIC had the opposite effect. AS-ODNs targeting luxS significantly decreased the aforementioned inhibitory effects of CAZ and the induction effects of CFP on E. coli biofilm formation. Therefore, biofilm formation by the E. coli clinical isolate E42 was evoked by CFP but attenuated by CAZ at sub-MICs, via a luxS/AI-2-based quorum sensing system. PMID:25189202

SHI, HUI-QING; SUN, FENG-JUN; CHEN, JIAN-HONG; YONG, XIAO-LAN; OU, QIAN-YI; FENG, WEI; XIA, PEI-YUAN

2014-01-01

352

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

353

Atypical Enteropathogenic Escherichia coli Secretes Plasmid Encoded Toxin  

PubMed Central

Plasmid encoded toxin (Pet) is a serine protease originally described in enteroaggregative Escherichia coli (EAEC) prototype strain 042 whose entire characterization was essentially obtained from studies performed with the purified toxin. Here we show that Pet is not exclusive to EAEC. Atypical enteropathogenic Escherichia coli (aEPEC) strains, isolated from diarrhea cases, express Pet and its detection in supernatants of infected HEp-2 cells coincides with the appearance of cell damage, which, in turn, were similar to those described with purified Pet. Pet secretion and the cytotoxic effects are time and culture medium dependent. In presence of DMEM supplemented with tryptone cell rounding and detachment were observed after just 5?h of incubation with the bacteria. In the absence of tryptone, the cytotoxic effects were detected only after 24?h of infection. We also show that, in addition to the prototype EAEC, other pet+ EAEC strains, also isolated from diarrhea cases, induce cellular damage in the same degree as the aEPEC. The cytotoxic effects of EAEC and aEPEC strains were significantly reduced in the presence of a serine protease inhibitor or anti-Pet IgG serum. Our results show a common aspect between the aEPEC and EAEC and provide the first evidence pointing to a role of Pet in aEPEC pathogenesis. PMID:24949475

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

2014-01-01

354

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

355

Characterization of Escherichia coli serotype O157:H7.  

PubMed Central

A total of 174 strains of Escherichia coli serotype O157:H7 representing human isolates obtained from outbreaks and sporadic cases of hemorrhagic colitis, hemolytic-uremic syndrome, and nonbloody diarrheal illnesses as well as from asymptomatic carriers across Canada and the United States were examined. E. coli serotype O157:H7 possessed distinct biochemical markers, a 100% negative reaction for beta-glucuronidase and sorbitol, and a 100% positive reaction for raffinose and dulcitol; all strains otherwise were biochemically typical of E. coli. The vast majority (97%) of the strains were susceptible to commonly used antimicrobial agents. All strains produced readily detectable levels of Verotoxin; however, with polymyxin extraction, nearly 50% of the strains showed up to a 10-fold increase in the toxin level. None were found to mediate hemagglutination of human group A erythrocytes with or without D-mannose. The majority (approximately 70%) of the strains showed localized and diffuse adherence to HEp-2 cells and Henle 407 cells, and the adherence patterns were not very different from those observed among other E. coli strains. Twenty phage types were recognized, with phage types 1 and 2 accounting for 65% of the test strains. Plasmid analysis indicated three basic plasmid profiles: profile I was characterized by 68.7- and 4.2-megadalton (MDa) plasmids (62% of strains), profile II was characterized by 66.2- and 1.8-MDa plasmids (20% of strains), and profile III was characterized by a 62.5-MDa plasmid (18% of strains). A small number (19%) of the strains carried at least one additional plasmid over the basic complements, and these could be considered to constitute a miscellaneous category. None of the above-described characteristics of E. coli serotype O157:H7 could be directly correlated with one another, with the nature of infection, or with the geographical distribution of strains. Images PMID:3053758

Ratnam, S; March, S B; Ahmed, R; Bezanson, G S; Kasatiya, S

1988-01-01

356

Nucleotide sequence of an Escherichia coli chromosomal hemolysin.  

PubMed Central

We determined the DNA sequence of an 8,211-base-pair region encompassing the chromosomal hemolysin, molecularly cloned from an O4 serotype strain of Escherichia coli. All four hemolysin cistrons (transcriptional order, C, A, B, and D) were encoded on the same DNA strand, and their predicted molecular masses were, respectively, 19.7, 109.8, 79.9, and 54.6 kilodaltons. The identification of pSF4000-encoded polypeptides in E. coli minicells corroborated the assignment of the predicted polypeptides for hlyC, hlyA, and hlyD. However, based on the minicell results, two polypeptides appeared to be encoded on the hlyB region, one similar in size to the predicted molecular mass of 79.9 kilodaltons, and the other a smaller 46-kilodalton polypeptide. The four hemolysin gene displayed similar codon usage, which is atypical for E. coli. This reflects the low guanine-plus-cytosine content (40.2%) of the hemolysin DNA sequence and suggests the non-E. coli origin of the hemolysin determinant. In vitro-derived deletions of the hemolysin recombinant plasmid pSF4000 indicated that a region between 433 and 301 base pairs upstream of the putative start of hlyC is necessary for hemolysin synthesis. Based on the DNA sequence, a stem-loop transcription terminator-like structure (a 16-base-pair stem followed by seven uridylates) in the mRNA was predicted distal to the C-terminal end of hlyA. A model for the general transcriptional organization of the E. coli hemolysin determinant is presented. Images PMID:3891743

Felmlee, T; Pellett, S; Welch, R A

1985-01-01

357

Codon Optimisation Is Key for Pernisine Expression in Escherichia coli  

PubMed Central

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

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

2015-01-01

358

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

Microsoft Academic Search

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

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

359

Finished Genome Sequence of Escherichia coli K-12 Strain HMS174 (ATCC 47011)  

PubMed Central

Escherichia coli strain K-12 substrain HMS174 is an engineered descendant of the E. coli K-12 wild-type strain. Like its ancestor, it is an important organism in biotechnological research and is used in fermentation processes for heterologous protein production. Here, we report the complete genome sequence of E. coli HMS174 (ATCC 47011). PMID:25414489

Mairhofer, Juergen; Krempl, Peter M.; Thallinger, Gerhard G.

2014-01-01

360

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

Microsoft Academic Search

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

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

2007-01-01

361

The Need and New Tools for Surveillance of Escherichia coli Pathogens  

Microsoft Academic Search

Summary Among foodborne pathogens, diarrhoeagenic Escherichia coli is of major concern beca- use of its commensal status, abundance in the natural environment, and ability to acquire virulence determinants by horizontal gene transfer from other microbes. From enterotoxi- genic E. coli (ETEC) strains to the more virulent enterohemorrhagic E. coli (EHEC), the me- chanisms of pathogenicity within this species are intriguing.

Asalapuram R. Pavankumar; Krishnan Sankaran

2008-01-01

362

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

363

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...

364

Escherichia coli diversity in livestock manures and agriculturally impacted stream waters  

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) influence E. coli fate and transport and therefore have important imp...

365

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

366

An auto-inducible Escherichia coli lysis system controlled by magnesium  

Microsoft Academic Search

The Escherichia coli (E. coli) prokaryotic expression system is widely used in the field of biology. The currently adopted processes for inducing cell wall rupture, in order to release the target protein, are complex and cumbersome. We developed an auto-inducible E. coli lysis system that is regulated by exogenous magnesium ion (Mg2+) concentration. This system is composed of a strictly

Xiaoming Zhang; Zhiming Pan; Qiang Fang; Jiayu Zheng; Maozhi Hu; Xinan Jiao

2009-01-01

367

Chemical and gravity dependent factors affecting Escherichia coli lag phase termination  

E-print Network

concentration gradients. The organism used for this study was Escherichia coli ATCC 4157. Acetic acid was not found in the extracellular environment of E. coli at the end of lag phase. Lactic acid was found in the extracellular environment of E. coli...

Elms, Rene ?Davina

2002-01-01

368

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

369

Effects of enteropathogenic Escherichia coli on microvillar membrane proteins during organ culture of rabbit intestinal mucosa  

Microsoft Academic Search

This study examines the effects of an enteropathogenic Escherichia coli on microvillar membrane proteins during organ culture of rabbit ileal explants. Explants maintained with enteropathogenic E coli showed brush border effacement affecting approximately 50% of enterocytes, and where enteropathogenic E coli were closely adherent to the enterocyte surface microvilli were apparently being shed as vesicles. The microvillar membrane enzymes alkaline

H Embaye; C A Hart; J N Fletcher; J R Saunders; R M Batt

1992-01-01

370

DETERMINATION OF PLASMID DNA CONCENTRATION MAINTAINED BY NONCULTURABLE ESCHERICHIA COLI IN MARINE MICROCOSMS  

EPA Science Inventory

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. . coli JM83 containing the plasmid pBR322 was placed in both sterile seawat...

371

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 ...

372

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

373

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

374

Effect of salt concentrations on the growth of heat-stressed and unstressed Escherichia coli  

Microsoft Academic Search

The effect sodium chloride (NaCl) and potassium chloride (KCl) concentration on the growth of Escherichia coli cells cultivated at 37 and 44°C was studied in an effort to understand the importance of the salts and glucose in medium to the growth of E. coli. A turbidimetric method was used to measure the growth of E. coli after a 24 hours

S. M. Abdulkarim; A. B. Fatimah; J. G. Anderson

375

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

376

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

377

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

378

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

PubMed Central

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

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

2015-01-01

379

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

380

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

381

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

382

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

PubMed Central

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

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

1993-01-01

383

Motility and Chemotaxis of Filamentous Cells of Escherichia coli  

PubMed Central

Filamentous cells of Escherichia coli can be produced by treatment with the antibiotic cephalexin, which blocks cell division but allows cell growth. To explore the effect of cell size on chemotactic activity, we studied the motility and chemotaxis of filamentous cells. The filaments, up to 50 times the length of normal E. coli organisms, were motile and had flagella along their entire lengths. Despite their increased size, the motility and chemotaxis of filaments were very similar to those properties of normal-sized cells. Unstimulated filaments of chemotactically normal bacteria ran and stopped repeatedly (while normal-sized bacteria run and tumble repeatedly). Filaments responded to attractants by prolonged running (like normal-sized bacteria) and to repellents by prolonged stopping (unlike normal-sized bacteria, which tumble), until adaptation restored unstimulated behavior (as occurs with normal-sized cells). Chemotaxis mutants that always ran when they were normal sized always ran when they were filament sized, and those mutants that always tumbled when they were normal sized always stopped when they were filament sized. Chemoreceptors in filaments were localized to regions both at the poles and at intervals along the filament. We suggest that the location of the chemoreceptors enables the chemotactic responses observed in filaments. The implications of this work with regard to the cytoplasmic diffusion of chemotaxis components in normal-sized and filamentous E. coli are discussed. PMID:10894745

Maki, Nazli; Gestwicki, Jason E.; Lake, Ellen M.; Kiessling, Laura L.; Adler, Julius

2000-01-01

384

Metabolic engineering of Escherichia coli for the production of xylonate.  

PubMed

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

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

2013-01-01

385

Microaerobic Conversion of Glycerol to Ethanol in Escherichia coli  

PubMed Central

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

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

2014-01-01

386

Metabolic engineering of Escherichia coli to produce zeaxanthin.  

PubMed

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

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

2015-04-01

387

Identification of Diarrheagenic Escherichia coli Strains from Avian Organic Fertilizers  

PubMed Central

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

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

2014-01-01

388

Biofilm formation by Escherichia coli in hypertonic sucrose media.  

PubMed

High osmotic environments produced by NaCl or sucrose have been used as reliable and traditional methods of food preservation. We tested, Escherichia coli as an indicator of food-contaminating bacterium, to determine if it can form biofilm in a hyperosmotic environment. E. coli K-12 IAM1264 did not form biofilm in LB broth that contained 1 M NaCl. However, the bacterium formed biofilm in LB broth that contained 1 M sucrose, although the planktonic growth was greatly suppressed. The biofilm, formed on solid surfaces, such as titer-plate well walls and glass slides, solely around the air-liquid interface. Both biofilm forming cells and planktonic cells in the hypertonic medium adopted a characteristic, fat and filamentous morphology with no FtsZ rings, which are a prerequisite for septum formation. Biofilm forming cells were found to be alive based on propidium iodide staining. The presence of 1 M sucrose in the food environment is not sufficient to prevent biofilm formation by E. coli. PMID:19447340

Kawarai, Taketo; Furukawa, Soichi; Narisawa, Naoki; Hagiwara, Chisato; Ogihara, Hirokazu; Yamasaki, Makari

2009-06-01

389

Structural interconversions modulate activity of Escherichia coli ribonucleotide reductase.  

PubMed

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

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

2011-12-27

390

Multidisciplinary response to the Escherichia coli 0104 outbreak in Europe.  

PubMed

The 2011 outbreak of Escherichia coli (E. coli) O104 in northern Germany resulted in over 4,100 illnesses, 900 cases of hemolytic uremic syndrome, and 50 deaths. The U.S. Army's Public Health Command Region-Europe established a multidisciplinary advisory team to prevent E. coli O104 exposure in the Department of Defense (DoD) population. This decentralized, interagency team engaged European public health authorities and coordinated control measures including risk communication. Following German public health investigations, the DoD advisory team compiled information from available official reports, assessed risk, and published guidance to halt the local procurement and supply of suspect foods for all DoD installations in Europe. Advisory team members processed outbreak information, adjusted advisories, and coordinated response efforts. The advisory team quickly identified authoritative information sources, coordinated case definitions, and streamlined potential case reporting. Timely and accurate risk assessment, management, and communication were vital in protecting the DoD population during this outbreak. There were no cases in DoD-related personnel. PMID:23198523

Dodd, Charles C; Cooper, Michael J

2012-11-01

391

Comprehensive Mapping of the Escherichia coli Flagellar Regulatory Network  

PubMed Central

Flagellar synthesis is a highly regulated process in all motile bacteria. In Escherichia coli and related species, the transcription factor FlhDC is the master regulator of a multi-tiered transcription network. FlhDC activates transcription of a number of genes, including some flagellar genes and the gene encoding the alternative Sigma factor FliA. Genes whose expression is required late in flagellar assembly are primarily transcribed by FliA, imparting temporal regulation of transcription and coupling expression to flagellar assembly. In this study, we use ChIP-seq and RNA-seq to comprehensively map the E. coli FlhDC and FliA regulons. We define a surprisingly restricted FlhDC regulon, including two novel regulated targets and two binding sites not associated with detectable regulation of surrounding genes. In contrast, we greatly expand the known FliA regulon. Surprisingly, 30 of the 52 FliA binding sites are located inside genes. Two of these intragenic promoters are associated with detectable noncoding RNAs, while the others either produce highly unstable RNAs or are inactive under these conditions. Together, our data redefine the E. coli flagellar regulatory network, and provide new insight into the temporal orchestration of gene expression that coordinates the flagellar assembly process. PMID:25275371

Fitzgerald, Devon M.; Bonocora, Richard P.; Wade, Joseph T.

2014-01-01

392

Engineered biosynthesis of medium-chain esters in Escherichia coli.  

PubMed

Medium-chain esters such as isobutyl acetate (IBAc) and isoamyl acetate (IAAc) are high-volume solvents, flavors and fragrances. In this work, we engineered synthetic metabolic pathways in Escherichia coli for the total biosynthesis of IBAc and IAAc directly from glucose. Our pathways harnessed the power of natural amino acid biosynthesis. In particular, the native valine and leucine pathways in E. coli were utilized to supply the precursors. Then alcohol acyltransferases from various organisms were investigated on their capability to catalyze esterification reactions. It was discovered that ATF1 from Saccharomyces cerevisiae was the best enzyme for the formation of both IBAc and IAAc in E. coli. In vitro biochemical characterization of ATF1 confirmed the fermentation results and provided rational guidance for future enzyme engineering. We also performed strain improvement by removing byproduct pathways (?ldh, ?poxB, ?pta) and increased the production of both target chemicals. Then the best IBAc producing strain was used for scale-up fermentation in a 1.3-L benchtop bioreactor. 36g/L of IBAc was produced after 72h fermentation. This work demonstrates the feasibility of total biosynthesis of medium-chain esters as renewable chemicals. PMID:25447641

Tai, Yi-Shu; Xiong, Mingyong; Zhang, Kechun

2015-01-01

393

Characterization of the YdeO Regulon in Escherichia coli  

PubMed Central

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

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

2014-01-01

394

Potential production platform of n-butanol in Escherichia coli.  

PubMed

We proposed a potential production platform of n-butanol in Escherichia coli. First, a butyrate-conversion strain was developed by removal of undesired genes and recruiting endogenous atoDA and Clostridium adhE2. Consequently, this E. coli strain grown on the M9 mineral salt with yeast extract (M9Y) was shown to produce 6.2g/L n-butanol from supplemented butyrate at 36h. The molar conversion yield of n-butanol on butyrate reaches 92%. Moreover, the production platform was advanced by additional inclusion of a butyrate-producing strain. This strain was equipped with a pathway comprising atoDA and heterologous genes for the synthesis of butyrate. Without butyrate, the butyrate-conversion and the butyrate-producing strains were co-cultured in M9Y medium and produced 5.5g/L n-butanol from glucose at 24h. The production yield on glucose accounts for 69% of the theoretical yield. Overall, it indicates a promise of the developed platform for n-butanol production in E. coli. PMID:25461833

Saini, Mukesh; Hong Chen, Min; Chiang, Chung-Jen; Chao, Yun-Peng

2015-01-01

395

Characterization of the YdeO regulon in Escherichia coli.  

PubMed

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

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

2014-01-01

396

Proteome reallocation in Escherichia coli with increasing specific growth rate.  

PubMed

Cells usually respond to changing growth conditions with a change in the specific growth rate (?) and adjustment of their proteome to adapt and maintain metabolic efficiency. Description of the principles behind proteome resource allocation is important for understanding metabolic regulation in response to changing ?. Thus, we analysed the proteome resource allocation dynamics of Escherichia coli into different metabolic processes in response to changing ?. E. coli was grown on minimal and defined rich media in steady state continuous cultures at different ? and characterised combining two LC-MS/MS-based proteomics methods: stable isotope labelling by amino acids in cell culture (SILAC) and intensity based label-free absolute quantification. We detected slowly growing cells investing more proteome resources in energy generation and carbohydrate transport and metabolism whereas for achieving faster growth cells needed to devote most resources to translation and processes closely related to the protein synthesis pipeline. Furthermore, down-regulation of energy generation and carbohydrate metabolism proteins with faster growth displayed very similar expression dynamics with the global transcriptional regulator CRP (cyclic AMP receptor protein), pointing to a dominant protein resource allocating role of this protein. Our data also suggest that acetate overflow may be the result of global proteome resource optimisation as cells saved proteome resources by switching from fully respiratory to respiro-fermentative growth. The presented results give a quantitative overview of how E. coli adjusts its proteome to achieve faster growth and in future could contribute to the design of more efficient cell factories through proteome optimisation. PMID:25712329

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

2015-03-17

397

Identification of diarrheagenic Escherichia coli strains from avian organic fertilizers.  

PubMed

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

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

2014-09-01

398

Rapid Method for Escherichia coli in the Cuyahoga River  

USGS Publications Warehouse

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

Brady, Amie M.G.

2007-01-01

399

Mobilization of Escherichia coli R1 silver-resistance plasmid pJT1 by Tn5Mob into Escherichia coli C600  

Microsoft Academic Search

Summary Escherichia coli Rl is an Ag+-resistant strain that, as we have shown recently, harbours at least two large plasmids, pJT1 (83 kb) and pJT2 (77 kb). Tn5-Mob was introduced into theE. coli Rl host replicon via conjugation on membrane filters. The transfer functions of plasmid RP4-4 were provided in this process and Tn5-Mob clones mated withE. coli C600 yielded

Mary-Ellen Starodub; Jack T. Trevors

1990-01-01

400

Escherichia coli O157:H7 and Other E. coli Strains Share Physiological Properties Associated with Intestinal Colonization  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli isolates(72 commensal and 10 O157:H7 isolates) were compared with regard to physiological and growth parameters related to their ability to survive and persist in the gastrointestinal tract and found to be similar. We propose that in nonhuman hosts E. coli O157:H7 strains function ...

401

Probiotic Escherichia coli Nissle 1917 reduces growth, Shiga toxin expression, release and thus cytotoxicity of enterohemorrhagic Escherichia coli.  

PubMed

Due to increased release or production of Shiga toxin by Enterohemorrhagic Escherichia coli (EHEC) after exposure to antimicrobial agents, the role of antimicrobial agents in EHEC mediated infections remains controversial. Probiotics are therefore rapidly gaining interest as an alternate therapeutic option. The well-known probiotic strain Escherichia coli Nissle 1917 (EcN) was tested in vitro to determine its probiotic effects on growth, Shiga toxin (Stx) gene expression, Stx amount and associated cytotoxicity on the most important EHEC strains of serotype O104:H4 and O157:H7. Following co-culture of EcN:EHEC in broth for 4 and 24 h, the probiotic effects on EHEC growth, toxin gene expression, Stx amount and cytotoxicity were determined using quantitative real time-PCR, Stx-ELISA and Vero cytotoxicity assays. Probiotic EcN strongly reduced EHEC numbers (cfu) of O104:H4 up to (68%) and O157:H7 to (72.2%) (p<0.05) in LB broth medium whereas the non-probiotic E. coli strain MG1655 had no effect on EHEC growth. The level of stx expression was significantly down-regulated, particularly for the stx2a gene. The stx down-regulation in EcN co-culture was not due to reduced numbers of EHEC. A significant inhibition in Stx amounts and cytotoxicity were also observed in sterile supernatants of EcN:EHEC co-cultures. These findings indicate that probiotic EcN displays strong inhibitory effects on growth, Shiga toxin gene expression, amount and cytotoxicity of EHEC strains. Thus, EcN may be considered as a putative therapeutic candidate, in particular against EHEC O104:H4 and O157:H7. PMID:25465158

Mohsin, Mashkoor; Guenther, Sebastian; Schierack, Peter; Tedin, Karsten; Wieler, Lothar H

2015-01-01

402

Risk Factors for Infection with Escherichia coli in Nursing Home Residents Colonized with Fluoroquinolone-Resistant E. coli.  

PubMed

A case-control study to determine risk factors for clinical infection with Escherichia coli was conducted among nursing home residents colonized with fluoroquinolone-resistant E. coli. Among 94 subjects, 11 (12%) developed infections with E. coli. Risk factors included the presence of a urinary catheter or tracheostomy, diabetes mellitus, and trimethoprim-sulfamethoxazole exposure. Infect Control Hosp Epidemiol 2015;00(0): 1-3. PMID:25880678

Manning, Sara; Lautenbach, Ebbing; Tolomeo, Pam; Han, Jennifer H

2015-05-01

403

Production of bioactive chicken follistatin315 in Escherichia coli.  

PubMed

Follistatin (FST) binds to myostatin (MSTN), a potent negative regulator of skeletal muscle growth. Inhibition of MSTN activity by FST treatment has shown to enhance muscle growth as well as ameliorate symptoms of muscular dystrophy in animal models, illustrating the potential of FST as an agent to enhance muscle growth in animal agriculture or to treat muscle wasting conditions or disease in humans. Therefore, we designed a study to produce biologically active recombinant chicken FST315 (chFST315) in an Escherichia coli host. Since FST contains multiple intramolecular disulfide bonds, we expressed chFST315 protein in either a system that utilizes a periplasmic expression strategy, or a genetically modified E. coli system (SHuffle strain) that is capable of disulfide bond formation in the cytoplasm. Periplasmic expression of chFST315 using the pMAL-p5x vector system, which was designed to express maltose-binding protein (MBP) fusion protein, failed to produce a soluble recombinant protein. However, cytoplasmic expression of chFST315 using pMAL-c5x vector in SHuffle E. coli strain resulted in a soluble expression of the recombinant protein (MBP-chFST315). Combination of heparin and amylose resin affinity chromatography yielded about 6 mg/L purified MBP-chFST315. The purified MBP-chFST315 showed binding affinity to MSTN and activin in a pull-down assay, as well as inhibited MSTN and activin activity in an in vitro reporter gene assay. In conclusion, results of the study demonstrate that for the first time a recombinant, biologically active FST molecule can be produced in a soluble form in E. coli. The ability to produce FST in a cost-effective system is expected to allow us to investigate the potentials of FST as an agent to improve skeletal muscle growth of meat producing animals via suppression of MSTN. PMID:25411099

Lee, Sang Beum; Choi, Rocky; Park, Sung Kwon; Kim, Yong Soo

2014-12-01

404

Preventing Foodborne Illness: Escherichia coli 0157:H7  

NSDL National Science Digital Library

This two-page, Center for Disease Control brochure provides excellent summary information on what E. coli 0157:H7 is, why it is a problem, how it is spread, and includes information on symptoms, diagnosis, and treatment. Available in HTML or ASCII text, this is a good introduction to the subject. Escherichia coli refers to a diverse family of hundreds of bacteria, many of which are permanent residents of human intestines, serving a beneficial purpose in digestion. The potentially deadly strain that has received recent publicity was first described in 1982, and is known as E. coli O157:H7. This strain of the bacteria produces a substance known as Vero-cytotoxin, which can cause severe illness, characterized by bloody diarrhea and occasional kidney failure in children and the elderly. Symptoms normally appear between three to six days after ingestion of the bacteria. Most illness associated with E. coli has been traced to eating undercooked, contaminated ground beef, although it can also be transmitted via person-to-person contact, by eating raw milk, contaminated vegetables or apple cider, and by swimming in or drinking sewage-contaminated water. The organism lives in the intestine of healthy cattle, and meat can become contaminated during slaughter. Because grinding mixes the bacteria into the product, ground meats represent a greater threat than do whole cuts. Contaminated meat looks and smells normal. Raw milk can be contaminated from bacteria present on a cow's udder. It appears that even small amounts of this organism can cause severe illness.

405

Characterization of three novel mechanosensitive channel activities in Escherichia coli  

PubMed Central

Mechanosensitive channels sense elevated membrane tension that arises from rapid water influx occurring when cells move from high to low osmolarity environments (hypoosmotic shock). These non-specific channels in the cytoplasmic membrane release osmotically-active solutes and ions. The two major mechanosensitive channels in Escherichia coli are MscL and MscS. Deletion of both proteins severely compromises survival of hypoosmotic shock. However, like many bacteria, E. coli cells possess other MscS-type genes (kefA, ybdG, ybiO, yjeP and ynaI). Two homologs, MscK (kefA) and YbdG, have been characterized as mechanosensitive channels that play minor roles in maintaining cell integrity. Additional channel openings are occasionally observed in patches derived from mutants lacking MscS, MscK and MscL. Due to their rare occurrence, little is known about these extra pressure-induced currents or their genetic origins. Here we complete the identification of the remaining E. coli mechanosensitive channels YnaI, YbiO and YjeP. The latter is the major component of the previously described MscM activity (~300 pS), while YnaI (~100 pS) and YbiO (~1000 pS) were previously unknown. Expression of native YbiO is NaCl-specific and RpoS-dependent. A ?7 strain was created with all seven E. coli mechanosensitive channel genes deleted. High level expression of YnaI, YbiO or YjeP proteins from a multicopy plasmid in the ?7 strain (MJFGH) leads to substantial protection against hypoosmotic shock. Purified homologs exhibit high molecular masses that are consistent with heptameric assemblies. This work reveals novel mechanosensitive channels and discusses the regulation of their expression in the context of possible additional functions. PMID:22874652

Edwards, Michelle D.; Black, Susan; Rasmussen, Tim; Rasmussen, Akiko; Stokes, Neil R.; Stephen, Terri-Leigh; Miller, Samantha; Booth, Ian R.

2012-01-01

406

Regulation of fatty acid biosynthesis in Escherichia coli.  

PubMed Central

Our understanding of fatty acid biosynthesis in Escherichia coli has increased greatly in recent years. Since the discovery that the intermediates of fatty acid biosynthesis are bound to the heat-stable protein cofactor termed acyl carrier protein, the fatty acid synthesis pathway of E. coli has been studied in some detail. Interestingly, many advances in the field have aided in the discovery of analogous systems in other organisms. In fact, E. coli has provided a paradigm of predictive value for the synthesis of fatty acids in bacteria and plants and the synthesis of bacterial polyketide antibiotics. In this review, we concentrate on four major areas of research. First, the reactions in fatty acid biosynthesis and the proteins catalyzing these reactions are discussed in detail. The genes encoding many of these proteins have been cloned, and characterization of these genes has led to a better understanding of the pathway. Second, the function and role of the two essential cofactors in fatty acid synthesis, coenzyme A and acyl carrier protein, are addressed. Finally, the steps governing the spectrum of products produced in synthesis and alternative destinations, other than membrane phospholipids, for fatty acids in E. coli are described. Throughout the review, the contribution of each portion of the pathway to the global regulation of synthesis is examined. In no other organism is the bulk of knowledge regarding fatty acid metabolism so great; however, questions still remain to be answered. Pursuing such questions should reveal additional regulatory mechanisms of fatty acid synthesis and, hopefully, the role of fatty acid synthesis and other cellular processes in the global control of cellular growth. PMID:8246839

Magnuson, K; Jackowski, S; Rock, C O; Cronan, J E

1993-01-01

407

Azorean wild rabbits as reservoirs of antimicrobial resistant Escherichia coli.  

PubMed

Antibiotic resistance in bacteria is an increasing problem that is not only constrained to the clinical setting but also to other environments that can lodge antibiotic resistant bacteria and therefore they may serve as reservoirs of genetic determinants of antibiotic resistance. One hundred and thirty-six faecal samples from European wild rabbits (Oryctolagus cuniculus algirus) were collected on São Jorge Island in Azores Archipelago, and analysed for Escherichia coli isolates. Seventy-seven isolates (56.6%) were recovered and studied for antimicrobial resistance, one isolate per positive sample. Thirteen (16.9%), 19 (24.7%), 25 (32.4%) and 20 (26%) isolates were ascribed to A, B1, B2 and D phylogenetic groups, respectively, by specific primer polymerase chain reaction. Different E. coli isolates were found to be resistant to ampicillin (16.9%), tetracycline (1.3%), streptomycin (42.9%), sulfamethoxazole-trimethoprim (1.3%), amikacin (1.3%), tobramycin (2.6%) and nalidixic acid (1.3%). Additionally, the blaTEM, tetA, strA/strB, aadA, sul1, intI, intI2 and qacE?+sul1 genes were found in most resistant isolates. This study showed that E. coli from the intestinal tract of wild rabbits from Azores Archipelago are resistant to widely prescribed antibiotics in medicine and they constitute a reservoir of antimicrobial resistant genes, which may play a significant role in the spread of antimicrobial resistance. Therefore, antibiotic resistant E. coli from Azorean wild rabbits may represent an ecological and public health problem. PMID:25246166

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

2014-12-01

408

A new Escherichia coli cell division gene, ftsK.  

PubMed Central

A mutation in a newly discovered Escherichia coli cell division gene, ftsK, causes a temperature-sensitive late-stage block in division but does not affect chromosome replication or segregation. This defect is specifically suppressed by deletion of dacA, coding for the peptidoglycan DD-carboxypeptidase, PBP 5. FtsK is a large polypeptide (147 kDa) consisting of an N-terminal domain with several predicted membrane-spanning regions, a proline-glutamine-rich domain, and a C-terminal domain with a nucleotide-binding consensus sequence. FtsK has extensive sequence identity with a family of proteins from a wide variety of prokaryotes and plasmids. The plasmid proteins are required for intercellular DNA transfer, and one of the bacterial proteins (the SpoIIIE protein of Bacillus subtilis) has also been implicated in intracellular chromosomal DNA transfer. PMID:7592387

Begg, K J; Dewar, S J; Donachie, W D

1995-01-01

409

Novel Antigens for enterotoxigenic Escherichia coli (ETEC) Vaccines  

PubMed Central

Enterotoxigenic Escherichia coli (ETEC) are the most common bacterial pathogens-causing diarrhea in developing countries where they cause hundreds of thousands of deaths, mostly in children. These organisms are leading cause of diarrheal illness in travelers to endemic countries. ETEC pathogenesis, and consequently vaccine approaches, have largely focused on plasmid-encoded enterotoxins or fimbrial colonization factors. To date these approaches have not yielded a broadly protective vaccine. However, recent studies suggest that ETEC pathogenesis is more complex than previously appreciated and involves additional plasmid and chromosomally-encoded virulence molecules that can be targeted in vaccines. Here, we review recent novel antigen discovery efforts, potential contribution of these proteins to the molecular pathogenesis of ETEC and protective immunity, and the potential implications for development of next generation vaccines for important pathogens. These proteins may help to improve the effectiveness of future vaccines by making simpler and possibly broadly protective because of their conserved nature. PMID:24702311

Fleckenstein, James M.; Sheikh, Alaullah; Qadri, Firdausi

2014-01-01

410

Enterotoxigenic Escherichia coli infection induces intestinal epithelial cell autophagy.  

PubMed

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

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

2014-06-25

411

Detergent (sodium dodecyl sulfate) shock proteins in Escherichia coli  

SciTech Connect

The protein composition of Escherichia coli W3110 grown in the presence and absence of 5% sodium dodecyl sulfate (SDS) was examined by two-dimensional gel electrophoresis. In SDS-grown cells, at least 4 proteins were turned on, 13 were turned off, 15 were elevated, and 15 were depressed. The 19 unique and elevated SDS-induced spots constituted 7.91% of the total 35S-labeled protein. There was no apparent overlap between these 19 detergent (SDS) stress proteins and those of other known bacterial stress responses. The detergent stress stimulon is a distinct and independent stimulon. Its physiological relevance probably derives from the presence of bile salts in animal gastrointestinal tracts.

Adamowicz, M.; Kelley, P.M.; Nickerson, K.W. (Univ. of Nebraska, Lincoln (USA))

1991-01-01

412

Engineering Escherichia coli to synthesize free fatty acids  

PubMed Central

Fatty acid metabolism has received significant attention as a route for producing high-energy density, liquid transportation fuels and high-value oleochemicals from renewable feedstocks. If microbes can be engineered to produce these compounds at yields that approach the theoretical limits of 0.3–0.4 g/g glucose, then processes can be developed to replace current petrochemical technologies. Here, we review recent metabolic engineering efforts to maximize production of free fatty acids (FFA) in Escherichia coli, the first step towards production of downstream products. To date, metabolic engineers have succeeded in achieving higher yields of FFA than any downstream products. Regulation of fatty acid metabolism and the physiological effects of fatty acid production will also be reviewed from the perspective of identifying future engineering targets. PMID:23102412

Lennen, Rebecca M.; Pfleger, Brian F.

2013-01-01

413

Sequencing and expression of the rne gene of Escherichia coli.  

PubMed Central

RNase E is a major endonucleolytic RNA processing enzyme in Escherichia coli. We have sequenced a 3.2 kb EcoRI-BamHI fragment encoding the rne gene, and identified its reading frame. Upstream from the gene, there are appropriate consensus sequences for a putative promoter and a ribosome binding site. We have translated this gene using a T7 RNA polymerase/promoter system. We determined 25 amino acids from the N-terminal of the translated product and they are in full agreement with the DNA sequence. The translated product of the rne gene migrates in SDS containing polyacrylamide gels as a 110,000 Da polypeptide, but the open reading frame found in the sequenced DNA indicates a much smaller protein. The entity that migrates as a 110,000 Da contains RNA, which could account, at least partially, for the migration of the rne gene product in SDS containing polyacrylamide gels. Images PMID:2011493

Chauhan, A K; Miczak, A; Taraseviciene, L; Apirion, D

1991-01-01

414

Nucleoside Triphosphate Pools in Synchronous Cultures of Escherichia coli1  

PubMed Central

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

Huzyk, Lydia; Clark, D. Joseph

1971-01-01

415

Implications of enterotoxigenic Escherichia coli genomics for vaccine development.  

PubMed

Enterotoxigenic Escherichia coli (ETEC) is a major cause of morbidity and mortality caused by diarrhea in children less than 5 years of age in low- and middle-income countries. Despite a wealth of research elucidating the mechanisms of disease, the immunological responses and vaccine development, ETEC is still relatively uncharacterized when it comes to regulation of virulence and detailed immune mechanisms. The recent emergence of next-generation sequencing now offers the possibility to screen genomes of ETEC strains isolated globally to identify novel vaccine targets in addition to those already established. In this review, we discuss how recent findings on ETEC genomics using novel sequencing techniques will aid in finding novel protective antigens that can be used in vaccine approaches. PMID:25540974

Sjöling, Åsa; von Mentzer, Astrid; Svennerholm, Ann-Mari

2015-04-01

416

Programming a Pavlovian-like conditioning circuit in Escherichia coli.  

PubMed

Synthetic genetic circuits are programmed in living cells to perform predetermined cellular functions. However, designing higher-order genetic circuits for sophisticated cellular activities remains a substantial challenge. Here we program a genetic circuit that executes Pavlovian-like conditioning, an archetypical sequential-logic function, in Escherichia coli. The circuit design is first specified by the subfunctions that are necessary for the single simultaneous conditioning, and is further genetically implemented using four function modules. During this process, quantitative analysis is applied to the optimization of the modules and fine-tuning of the interconnections. Analogous to classical Pavlovian conditioning, the resultant circuit enables the cells to respond to a certain stimulus only after a conditioning process. We show that, although the conditioning is digital in single cells, a dynamically progressive conditioning process emerges at the population level. This circuit, together with its rational design strategy, is a key step towards the implementation of more sophisticated cellular computing. PMID:24434523

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

2014-01-01

417

Programming a Pavlovian-like conditioning circuit in Escherichia coli  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

418

Functional biosynthesis of an allophycocyan beta subunit in Escherichia coli.  

PubMed

Allophycocyanin is a phycobiliprotein with various biological and pharmacological properties. An expression vector was constructed using CpeS as the bilin lyase for the allophycocyanin beta subunit, resulting in overexpression of a fluorescent allophycocyanin beta-subunit in Escherichia coli. A high-density cell culture was developed using a continuous feeding strategy. After 16 h of culture, the dry cell density reached 21.4 g l(-1), the expression of the allophycocyanin beta-subunit was 0.86 g l(-1) broth, and the relative chromoprotein yield was 81.4%. The recombinant protein showed spectral features similar to native allophycocyanin, which provide an efficient methodology for large-scale production of this valuable fluorescent protein. PMID:19269586

Ge, Baosheng; Sun, Haixiang; Feng, Yang; Yang, Jinying; Qin, Song

2009-03-01

419

Phenotypic bistability in Escherichia coli's central carbon metabolism.  

PubMed

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

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

2014-01-01

420

Failed Escape: Solid Surfaces Prevent Tumbling of Escherichia coli  

NASA Astrophysics Data System (ADS)

Understanding how bacteria move close to surfaces is crucial for a broad range of microbial processes including biofilm formation, bacterial dispersion, and pathogenic infections. We used digital holographic microscopy to capture a large number (>103) of three-dimensional Escherichia coli trajectories near and far from a surface. We found that within 20 ?m from a surface tumbles are suppressed by 50% and reorientations are largely confined to surface-parallel directions, preventing escape of bacteria from the near-surface region. A hydrodynamic model indicates that the tumble suppression is likely due to a surface-induced reduction in the hydrodynamic force responsible for the flagellar unbundling that causes tumbling. These findings imply that tumbling does not provide an effective means to escape trapping near surfaces.

Molaei, Mehdi; Barry, Michael; Stocker, Roman; Sheng, Jian

2014-08-01

421

Phenotypic bistability in Escherichia coli's central carbon metabolism  

PubMed Central

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

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

2014-01-01

422

Failed escape: solid surfaces prevent tumbling of Escherichia coli.  

PubMed

Understanding how bacteria move close to surfaces is crucial for a broad range of microbial processes including biofilm formation, bacterial dispersion, and pathogenic infections. We used digital holographic microscopy to capture a large number (>10(3)) of three-dimensional Escherichia coli trajectories near and far from a surface. We found that within 20???m from a surface tumbles are suppressed by 50% and reorientations are largely confined to surface-parallel directions, preventing escape of bacteria from the near-surface region. A hydrodynamic model indicates that the tumble suppression is likely due to a surface-induced reduction in the hydrodynamic force responsible for the flagellar unbundling that causes tumbling. These findings imply that tumbling does not provide an effective means to escape trapping near surfaces. PMID:25148353

Molaei, Mehdi; Barry, Michael; Stocker, Roman; Sheng, Jian

2014-08-01

423

Intimate host attachment: enteropathogenic and enterohaemorrhagic Escherichia coli  

PubMed Central

Enteropathogenic and enterohaemorrhagic Escherichia coli use a novel infection strategy to colonize the gut epithelium, involving translocation of their own receptor, Tir, via a type III secretion system and subsequent formation of attaching and effecting (A/E) lesions. Following integration into the host cell plasma membrane of cultured cells, and clustering by the outer membrane adhesin intimin, Tir triggers multiple actin polymerization pathways involving host and bacterial adaptor proteins that converge on the host Arp2/3 actin nucleator. Although initially thought to be involved in A/E lesion formation, recent data have shown that the known Tir-induced actin polymerization pathways are dispensable for this activity, but can play other major roles in colonization efficiency, in vivo fitness and systemic disease. In this review we summarize the roadmap leading from the discovery of Tir, through the different actin polymerization pathways it triggers, to our current understanding of their physiological functions. PMID:23927593

Lai, YuShuan; Rosenshine, Ilan; Leong, John M.; Frankel, Gad

2013-01-01

424

Towards reassigning the rare AGG codon in Escherichia coli.  

PubMed

The rare AGG codon in Escherichia coli has been reassigned to code non-canonical amino acids (ncAAs) by using the PylRS-tRNA(Pyl)(CCU) pair. When N(?) -alloc-lysine was used as a PylRS substrate, almost quantitative occupancy of N(?) -alloc-lysine at an AGG codon site was achieved in minimal medium. ncAAs can be potentially incorporated at the AGG codon with varying efficiencies, depending on their activities towards corresponding enzymes. As AGG is a sense codon, the approach reported here resolves the typical low ncAA incorporation issue that has been associated with ncAA mutagenesis and therefore allows bulk preparation of proteins with site-selectively incorporated ncAAs for applications such as therapeutic protein production. PMID:25044341

Zeng, Yu; Wang, Wei; Liu, Wenshe R

2014-08-18

425

Detection of Escherichia coli in the sewage influent by fluorescent labeled T4 phage  

Microsoft Academic Search

For a precise estimation of sanitary condition, Escherichia coli detection system using E. coli-specific bacteriophage T4 was constructed. To facilitate E. coli detection, T4e? phage which did not produce the lysozyme was constructed and green fluorescent protein (GFP) was displayed on T4e? small outer capside (SOC) protein. This T4e?\\/GFP can detect E. coli K12 without cell lysis. In this study,

Kazuhiko Miyanaga; Tomonori Hijikata; Chiaki Furukawa; Hajime Unno; Yasunori Tanji

2006-01-01

426

Simple route for the detection of Escherichia coli using quantum dots  

Microsoft Academic Search

We have demonstrated a simple route for the detection of Escherichia coli using well plates with quantum dot (QD) fluorescent labels. The genetically engineered E. coli strain DH5?, containing green fluorescent protein (GFP), was used as the model system. Two approaches were employed in the\\u000a detection of E. coli. In the first method, E. coli were specifically adhered onto a

Pan Kee Bae; Hye-Mi So; Kyung Nam Kim; Hwa Sung You; Kang Sik Choi; Chang Hae Kim; Jeong-Kyu Park; Jeong-O. Lee

2010-01-01

427

Characterization of Escherichia coli Strains from Cases of Childhood Diarrhea in Provincial Southwestern Nigeria  

Microsoft Academic Search

In a study carried out in small-town and rural primary health care centers in southwestern Nigeria, 330 Escherichia coli strains isolated from 187 children with diarrhea and 144 apparently healthy controls were examined for virulence traits. Based on the results of colony blot hybridization, strains were categorized as enteropathogenic E. coli (1.8%), enterotoxigenic E. coli (2.4%), enteroinvasive E. coli (1.2%),

IRUKA N. OKEKE; ADEBAYO LAMIKANRA; HARTMUT STEINRUCK; JAMES B. KAPER

2000-01-01

428

Occurrence of Genes Associated with Enterotoxigenic and Enterohemorrhagic Escherichia coli in Agricultural Waste Lagoons  

Microsoft Academic Search

The prevalence among all Escherichia coli bacteria of the LTIIa toxin gene and STII toxin gene, both associated with enterotoxigenic E. coli, and of three genes (stxI, stxII, and eaeA) associated with enterohemor- rhagic E. coli was determined in farm waste disposal systems seasonally for 1 year. Single- and nested-PCR results for the number of E. coli isolates carrying each

Eunice C. Chern; Yu-Li Tsai; Betty H. Olson

2004-01-01

429

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

PubMed Central

ABSTRACT A recent study published in mBio [Y. H. Grad et al., mBio 4(1):e00452-12, 2013] indicates that a rapid introgressive evolution has occurred in Escherichia coli O104:H4 by sequential acquisition of foreign genetic material involving pathogenicity traits. O104 genetic promiscuity cannot be readily explained by high population sizes. However, extensive interactions leading to cumulative assemblies of pathogenicity genes might be assured by small K-strategist populations exploiting particular intestinal niches. Next-generation sequencing technologies will be critical to detect particular “gene cocktails” as potentially pathogenic ensembles and to predict the risk of future outbreaks. PMID:23422408

Baquero, Fernando; Tobes, Raquel

2013-01-01

430

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

PubMed Central

The main features of enteroaggregative Escherichia coli (EAEC) pathogenesis include attachment of bacteria to the intestinal mucosa, production of various toxins and cytotoxins, and stimulation of mucosal inflammation. ‘Virulence’ genes encode these features. Comparison of different EAEC isolates has shown that the virulence gene content of these isolates varies considerably. The heterogeneity of EAEC strains was concluded from the results obtained from the volunteer as well as other studies. Although the underlying mechanism behind the apparent increase in O104:H4 virulence is not known, several bacterial factors have been implicated. In this review, the known virulence factors involved in pathogenesis of EAEC pathotype are summarized. PMID:24834248

Jafari, Anis; Aslani, Mohammad Mehdi

2013-01-01

431

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

PubMed

Diarrheagenic Escherichia coli pathotypes (DEP) are important foodborne pathogens in various countries, including Mexico. However, no data exist on the presence of DEP on fresh tomatoes (Solanum lycopericum) from Mexico. The frequency of fecal coliforms (FC), E. coli, and DEP were determined for two tomato varieties. One hundred samples of a saladette tomato variety and 100 samples of a red round tomato variety were collected from public markets in Pachuca, Mexico. Each tomato sample consisted of four whole tomatoes. For the 100 saladette samples, coliform bacterial, FC, E. coli, and DEP were identified in 100, 70, 60, and 10% of samples, respectively. For the 100 red round samples, coliform bacterial, FC, E. coli, and DEP were identified in 100, 75, 65, and 11% of samples, respectively. Identified DEP included Shiga toxin-producing E. coli (STEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC). STEC were isolated from 6% of saladette samples and 5% of red round samples. ETEC were isolated from 3% of saladette samples and 4% of red round samples. EPEC were isolated from 2% of saladette samples and 3% of red round samples, and EIEC were isolated from 1% of saladette samples. Both STEC and ETEC were identified in two saladette samples and 1 red round sample. E. coli O157:H7 was not detected in any STEC-positive samples. PMID:23992508

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

2013-09-01

432

A new Thermus-Escherichia coli shuttle integration vector system.  

PubMed Central

We established a Thermus thermophilus strain in which the pyrE gene (coding for orotate phosphoribosyltransferase of the pyrimidine biosynthetic pathway) was totally deleted. We also constructed an integration vector, which consisted of the Escherichia coli plasmid vector pBluescript and a 2.1-kb segment of the T. thermophilus leu operon sequence, for the integration of a foreign gene into a chromosome of the thermophile. pyrE and leuB genes were used as probes to test the integration vector. The integration vector pINV, bearing the pyrE gene, transformed the delta pyrE strain at a frequency of 6 x 10(-5) through a single crossover event. The leuB gene could also be used as another marker of the integration vector system. The vector could be integrated at the expected site. By digesting the chromosomal DNA of the T. thermophilus transformants with a unique restriction enzyme, the vector could be recovered into E. coli after the recircularization in vitro. The kanamycin nucleotidyltransferase gene could be successfully expressed in the thermophile by using pINV. PMID:9244269

Tamakoshi, M; Uchida, M; Tanabe, K; Fukuyama, S; Yamagishi, A; Oshima, T

1997-01-01

433

Bacteriophages with the Ability to Degrade Uropathogenic Escherichia Coli Biofilms  

PubMed Central

Escherichia coli-associated urinary tract infections (UTIs) are among the most common bacterial infections in humans. UTIs are usually managed with antibiotic therapy, but over the years, antibiotic-resistant strains of uropathogenic E. coli (UPEC) have emerged. The formation of biofilms further complicates the treatment of these infections by making them resistant to killing by the host immune system as well as by antibiotics. This has encouraged research into therapy using bacteriophages (phages) as a supplement or substitute for antibiotics. In this study we characterized 253 UPEC in terms of their biofilm-forming capabilities, serotype, and antimicrobial resistance. Three phages were then isolated (vB_EcoP_ACG-C91, vB_EcoM_ACG-C40 and vB_EcoS_ACG-M12) which were able to lyse 80.5% of a subset (42) of the UPEC strains able to form biofilms. Correlation was established between phage sensitivity and specific serotypes of the UPEC strains. The phages’ genome sequences were determined and resulted in classification of vB_EcoP_ACG-C91 as a SP6likevirus, vB_EcoM_ACG-C40 as a T4likevirus and vB_EcoS_ACG-M12 as T1likevirus. We assessed the ability of the three phages to eradicate the established biofilm of one of the UPEC strains used in the study. All phages significantly reduced the biofilm within 2–12 h of incubation. PMID:22590682

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

2012-01-01

434

Enterotoxigenic Escherichia coli virulence factors and vaccine approaches.  

PubMed

Enterotoxigenic Escherichia coli (ETEC) is recognized as one of the major causes of infectious diarrhea in developing countries. Worldwide, the incidence of ETEC infections is estimated to result in 650 million cases of diarrhea and 380,000 deaths in children under 5 years of age. ETEC is also an important cause of travelers' diarrhea in people traveling to endemic regions of the world. Although ETEC is an uncommon cause of infections in the USA, there have been 14 reported outbreaks of ETEC in the USA and seven on cruise ships over the 20-year period between 1975 and 1995. ETEC strains are comprised of a large number of serotypes that produce a variety of colonization factors and enterotoxins. On infection, ETEC first establishes itself by adhering to the epithelium of the small intestine via one or more colonization factor antigens or coli surface proteins. Once established, ETEC expresses one or more enterotoxin(s), which results in the production of secretory diarrhea. While the need for an efficacious, easily administered vaccine is great, there are currently no licensed ETEC vaccines available for use in endemic countries or for US travelers. PMID:15485338

Sizemore, Donata R; Roland, Kenneth L; Ryan, Una S

2004-10-01

435

A surface accumulator of Escherichia coli in water flow.  

PubMed

The objective of this research is to design and optimise a mini/micro-channel based surface accumulator of Escherichia coli to be detected by acoustic wave biosensors. A computational research has been carried out using the state of the art software, CFD-ACE with water as bacteria bearing fluid. E. coli bacteria have been modelled as random discrete particles tracked by solving the Lagrangian equations. The design challenges are to achieve low shear force (pico-N), high concentration at accumulation and high enough Reynolds number to avoid bacteria swimming. A range of low Reynolds number (Re) from 28.2 to 58.3 has been considered along with the effects of particle-boundary interactions, gravity, Saffman lift and Magnus lift. About four orders of magnitude higher concentration at accumulation than the inlet concentration and lower shear force in the order of less than pico-N have been achieved in the optimised design with particles accumulating at a specific location under random particle-boundary interactions. PMID:18663613

Mayeed, M S; Al-Mekhnaqi, A M; Auner, G W; Newaz, G M

2009-02-01

436

Stress response of Escherichia coli to elevated hydrostatic pressure.  

PubMed Central

The response of exponentially growing cultures of Escherichia coli to abrupt shifts in hydrostatic pressure was studied. A pressure upshift to 546 atm (55,304 kPa) of hydrostatic pressure profoundly perturbed cell division, nucleoid structure, and the total rate of protein synthesis. The number of polypeptides synthesized at increased pressure was greatly reduced, and many proteins exhibited elevated rates of synthesis relative to total protein synthesis. We designated the latter proteins pressure-induced proteins (PIPs). The PIP response was transient, with the largest induction occurring approximately 60 to 90 min postshift. Fifty-five PIPs were identified. Many of these proteins are also induced by heat shock or cold shock. The PIP demonstrating the greatest pressure induction was a basic protein of 15.6 kDa. High pressure inhibits growth but does not inhibit the synthesis of stringently controlled proteins. Cold shock is the only additional signal which has been found to elicit this type of response. These data indicate that elevated pressure induces a unique stress response in E. coli, the further characterization of which could be useful in delineating its inhibitory nature. Images PMID:8226663

Welch, T J; Farewell, A; Neidhardt, F C; Bartlett, D H

1993-01-01

437

Escherichia coli genes expressed preferentially in an aquatic environment.  

PubMed

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

Espinosa-Urgel, M; Kolter, R

1998-04-01

438

Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation  

PubMed Central

Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe–S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound cytochromes and an expressed human cystathionine beta-synthase (CBS). The presence of CoPPIX in cytochromes inhibited their electron transport capacity and resulted in a substantially decreased respiration. Bacterial cells adapted to the increased cobalt concentration by inducing a modified mixed acid fermentative pathway under aerobiosis. We capitalized on the ability of E. coli to insert cobalt into PPIX to carry out an expression of CoPPIX-substituted heme proteins. The level of CoPPIX-substitution increased with the number of passages of cells in a cobalt-containing medium. This approach is an inexpensive method to prepare cobalt-substituted heme proteins compared to in vitro enzyme reconstitution or in vivo replacement using metalloporphyrin heme analogs and seems to be especially suitable for complex heme proteins with an additional coenzyme, such as human CBS. PMID:21184140

Majtan, Tomas; Frerman, Frank E.

2011-01-01

439

Galactose-specific messenger ribonucleic acid contents in Escherichia coli  

PubMed Central

A method is described for measuring the proportion of galactose-specific mRNA (gal-mRNA) in the total RNA extracted from pulse-labelled cells of Escherichia coli K12, by DNA–RNA hybridization with DNA prepared from bacteriophage ?dg. RNA from wild-type E. coli was compared with RNA from a homogenote carrying the gal operon both in the chromosome and in a substituted sex-factor, and with RNA from a deletion strain that carried the galactose operon only in the exogenote. In each case the cultures were induced with fucose. Under these conditions the amount of gal-mRNA was found to be proportional to the content of galactokinase in the different cultures, and to the gene frequency. The amounts of gal-mRNA in an Oc mutant and an R? mutant were also proportional to the observed contents of galactokinase. In cultures repressed for the enzymes of the galactose operon with thiomethylgalactoside, the content of gal-mRNA was higher than expected from the content of galactokinase. Possible explanations of this finding are discussed. PMID:4940376

Gosden, J. R.; Irving, M. I.; Bishop, J. O.

1971-01-01

440

In vivo immobilization of D-hydantoinase in Escherichia coli.  

PubMed

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

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

2014-07-01

441

Proteomic adaptations to starvation prepare Escherichia coli for disinfection tolerance.  

PubMed

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

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

2015-02-01

442

Chemotactic adaptation kinetics of individual Escherichia coli cells  

PubMed Central

Escherichia coli chemotaxis serves as a paradigm for the way living cells respond and adapt to changes in their environment. The chemotactic response has been characterized at the level of individual flagellar motors and in populations of swimming cells. However, it has not been previously possible to quantify accurately the adaptive response of a single, multiflagellated cell. Here, we use our recently developed optical trapping technique to characterize the swimming behavior of individual bacteria as they respond to sudden changes in the chemical environment. We follow the adaptation kinetics of E. coli to varying magnitudes of step-up and step-down changes in concentration of chemoattractant. We quantify two features of adaptation and how they vary with stimulus strength: abruptness (the degree to which return to prestimulus behavior occurs within a small number of run/tumble events) and overshoot (the degree of excessive response before the return to prestimulus behavior). We also characterize the asymmetry between step-up and step-down responses, observed at the single-cell level. Our findings provide clues to an improved understanding of chemotactic adaptation. PMID:22679285

Min, Taejin L.; Mears, Patrick J.; Golding, Ido; Chemla, Yann R.

2012-01-01

443

Sonolysis of Escherichia coli and Pichia pastoris in microfluidics.  

PubMed

We report on an efficient ultrasound based technique for lysing Escherichia coli and Pichia pastoris with oscillating cavitation bubbles in an integrated microfluidic system. The system consists of a meandering microfluidic channel and four piezoelectric transducers mounted on a glass substrate, with the ultrasound exposure and gas pressure regulated by an automatic control system. Controlled lysis of bacterial and yeast cells expressing green fluorescence protein (GFP) is studied with high-speed photography and fluorescence microscopy, and quantified with real-time polymerase chain reaction (qRT-PCR) and fluorescence intensity. The effectiveness of cell lysis correlates with the duration of ultrasound exposure. Complete lysis can be achieved within one second of ultrasound exposure with a temperature increase of less than 3.3 °C. The rod-shaped E. coli bacteria are disrupted into small fragments in less than 0.4 seconds, while the more robust elliptical P. pastoris yeast cells require around 1.0 second for complete lysis. Fluorescence intensity measurements and qRT-PCR analysis show that functionality of GFP and genomic DNA for downstream analytical assays is maintained. PMID:22183135

Tandiono, Tandiono; Ow, Dave Siak-Wei; Driessen, Leonie; Chin, Cara Sze-Hui; Klaseboer, Evert; Choo, Andre Boon-Hwa; Ohl, Siew-Wan; Ohl, Claus-Dieter

2012-02-21

444

Mutants of Escherichia coli deficient in the fermentative lactate dehydrogenase  

SciTech Connect

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

Mat-Jan, F.; Alam, K.Y.; Clark, D.P. (Southern Illinois Univ., Carbondale (USA))

1989-01-01

445

Escherichia coli alkaline phosphatase. Kinetic studies with the tetrameric enzyme  

PubMed Central

1. The stability of the tetrameric form of Escherichia coli alkaline phosphatase was examined by analytical ultracentrifugation. 2. The stopped-flow technique was used to study the hydrolysis of nitrophenyl phosphates by the alkaline phosphatase tetramer at pH7.5 and 8.3. In both cases transient product formation was observed before the steady state was attained. Both transients consisted of the liberation of 1mol of nitrophenol/2mol of enzyme subunits within the dead-time of the apparatus. The steady-state rates were identical with those observed with the dimer under the same conditions. 3. The binding of 2-hydroxy-5-nitrobenzyl phosphonate to the alkaline phosphatase tetramer was studied by the temperature-jump technique. The self-association of two dimers to form the tetramer is linked to a conformation change within the dimer. This accounts for the differences between the transient phases in the reactions of the dimer and the tetramer with substrate. 4. Addition of Pi to the alkaline phosphatase tetramer caused it to dissociate into dimers. The tetramer is unable to bind this ligand. It is suggested that the tetramer undergoes a compulsory dissociation before the completion of its first turnover with substrate. 5. On the basis of these findings a mechanism is proposed for the involvement of the alkaline phosphatase tetramer in the physiology of E. coli. PMID:4561386

Halford, S. E.; Schlesinger, M. J.; Gutfreund, H.

1972-01-01

446

Rational design of Escherichia coli for L-isoleucine production.  

PubMed

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

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

2012-11-16

447

Structure and biochemical activities of Escherichia coli MgsA.  

PubMed

Bacterial "maintenance of genome stability protein A" (MgsA) and related eukaryotic enzymes play important roles in cellular responses to stalled DNA replication processes. Sequence information identifies MgsA enzymes as members of the clamp loader clade of AAA+ proteins, but structural information defining the family has been limited. Here, the x-ray crystal structure of Escherichia coli MgsA is described, revealing a homotetrameric arrangement for the protein that distinguishes it from other clamp loader clade AAA+ proteins. Each MgsA protomer is composed of three elements as follows: ATP-binding and helical lid domains (conserved among AAA+ proteins) and a tetramerization domain. Although the tetramerization domains bury the greatest amount of surface area in the MgsA oligomer, each of the domains participates in oligomerization to form a highly intertwined quaternary structure. Phosphate is bound at each AAA+ ATP-binding site, but the active sites do not appear to be in a catalytically competent conformation due to displacement of Arg finger residues. E. coli MgsA is also shown to form a complex with the single-stranded DNA-binding protein through co-purification and biochemical studies. MgsA DNA-dependent ATPase activity is inhibited by single-stranded DNA-binding protein. Together, these structural and biochemical observations provide insights into the mechanisms of MgsA family AAA+ proteins. PMID:21297161

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

2011-04-01

448

Three Mutations in Escherichia coli That Generate Transformable Functional Flagella  

PubMed Central

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

Wang, Wenjing; Jiang, Zhengzeng; Westermann, Martin

2012-01-01

449

Metabolic engineering of itaconate production in Escherichia coli.  

PubMed

Interest in sustainable development has led to efforts to replace petrochemical-based monomers with biomass-based ones. Itaconic acid, a C5-dicarboxylic acid, is a potential monomer for the chemical industry with many prospective applications. cis-aconitate decarboxylase (CadA) is the key enzyme of itaconate production, converting the citric acid cycle intermediate cis-aconitate into itaconate. Heterologous expression of cadA from Aspergillus terreus in Escherichia coli resulted in low CadA activities and production of trace amounts of itaconate on Luria-Bertani (LB) medium (<10 mg/L). CadA was primarily present as inclusion bodies, explaining the low activity. The activity was significantly improved by using lower cultivation temperatures and mineral medium, and this resulted in enhanced itaconate titres (240 mg/L). The itaconate titre was further increased by introducing citrate synthase and aconitase from Corynebacterium glutamicum and by deleting the genes encoding phosphate acetyltransferase and lactate dehydrogenase. These deletions in E. coli's central metabolism resulted in the accumulation of pyruvate, which is a precursor for itaconate biosynthesis. As a result, itaconate production in aerobic bioreactor cultures was increased up to 690 mg/L. The maximum yield obtained was 0.09 mol itaconate/mol glucose. Strategies for a further improvement of itaconate production are discussed. PMID:25277412

Vuoristo, Kiira S; Mars, Astrid E; Sangra, Jose Vidal; Springer, Jan; Eggink, Gerrit; Sanders, Johan P M; Weusthuis, Ruud A

2015-01-01

450

Comparative Genomics of Escherichia coli Strains Causing Urinary Tract Infections ? †  

PubMed Central

The virulence determinants of uropathogenic Escherichia coli have been studied extensively over the years, but relatively little is known about what differentiates isolates causing various types of urinary tract infections. In this study, we compared the genomic profiles of 45 strains from a range of different clinical backgrounds, i.e., urosepsis, pyelonephritis, cystitis, and asymptomatic bacteriuria (ABU), using comparative genomic hybridization analysis. A microarray based on 31 complete E. coli sequences was used. It emerged that there is little correlation between the genotypes of the strains and their disease categories but strong correlation between the genotype and the phylogenetic group association. Also, very few genetic differences may exist between isolates causing symptomatic and asymptomatic infections. Only relatively few genes that could potentially differentiate between the individual disease categories were identified. Among these were two genomic islands, namely, pathogenicity island (PAI)-CFT073-serU and PAI-CFT073-pheU, which were significantly more associated with the pyelonephritis and urosepsis isolates than with the ABU and cystitis isolates. These two islands harbor genes encoding virulence factors, such as P fimbriae (pyelonephritis-associated fimbriae) and an important immunomodulatory protein, TcpC. It seems that both urovirulence and growth fitness can be attributed to an assortment of genes rather than to a specific gene set. Taken together, urovirulence and fitness are the results of the interplay of a mixture of factors taken from a rich menu of genes. PMID:21421782

Vejborg, Rebecca Munk; Hancock, Viktoria; Schembri, Mark A.; Klemm, Per

2011-01-01

451

Functional analysis of the uropathogenic Escherichia coli R049 gene.  

PubMed

The objective of this study was to determine the function of the novel uropathogenic Escherichia coli (UPEC) gene R049 during host infection. We infected the urinary tracts of mice with E. coli UPEC132 or the R049 deletion mutant UPEC132?R049.The mouse kidneys were harvested at 4 and 8h post-infection and screened for differentially expressed genes by microarray analysis. We identified 379 and 515 differentially expressed genes at 4 and 8 h post-infection, respectively. Thirty-four of these genes were associated with inflammatory and immune signaling pathways, including those related to mitogen-activated protein kinase signaling, leukocyte transendothelial migration, cytokine-cytokine receptor interaction, Toll-like receptor signaling, and apoptosis. Protein binding (GO 0005515) was the most prevalent molecular function in the Gene Ontology terms related to differentially expressed genes. In conclusion, R049 expression in UPEC132 is related to the early innate immune and inflammatory responses in UPEC-infected hosts. This work lays the foundation for further research on anti-infective immunity against UPEC. PMID:25644951

Yang, Dongjing; Dong, Jie; Su, Xu; Zhang, Wei; Zhang, Li; Li, Li; Lv, Likun; Guo, Liru

2015-02-01

452

Understanding carbon catabolite repression in Escherichia coli using quantitative models.  

PubMed

Carbon catabolite repression (CCR) controls the order in which different carbon sources are metabolized. Although this system is one of the paradigms of the regulation of gene expression in bacteria, the underlying mechanisms remain controversial. CCR involves the coordination of different subsystems of the cell that are responsible for the uptake of carbon sources, their breakdown for the production of energy and precursors, and the conversion of the latter to biomass. The complexity of this integrated system, with regulatory mechanisms cutting across metabolism, gene expression, and signaling, and that are subject to global physical and physiological constraints, has motivated important modeling efforts over the past four decades, especially in the enterobacterium Escherichia coli. Different hypotheses concerning the dynamic functioning of the system have been explored by a variety of modeling approaches. We review these studies and summarize their contributions to the quantitative understanding of CCR, focusing on diauxic growth in E. coli. Moreover, we propose a highly simplified representation of diauxic growth that makes it possible to bring out the salient features of the models proposed in the literature and confront and compare the explanations they provide. PMID:25475882

Kremling, A; Geiselmann, J; Ropers, D; de Jong, H

2015-02-01

453

Pattern Formation of Bacterial Colonies by Escherichia coli  

NASA Astrophysics Data System (ADS)

We have studied the morphological diversity and change in bacterial colonies, using the bacterial species Escherichia coli, as a function of both agar concentration Ca and nutrient concentration Cn. We observed various colony patterns, classified them into four types by pattern characteristics and established a morphological diagram by dividing it into four regions. They are regions A [diffusion-limited aggregation (DLA)-like], B (Eden-like), C (concentric-ring), and D (fluid-spreading). In particular, we have observed a concentric-ring colony growth for E. coli. We focused on the periodic growth in region C and obtained the following results: (i) A colony grows cyclically with the growing front repeating an advance (migration phase) and a momentary rest (consolidation phase) alternately. (ii) The growth width L and the bulge width W in one cycle decrease asymptotically to certain values, when Ca is increased. (iii) L does not depend on Cn, while W is an increasing function of Cn. Plausible mechanisms are proposed to explain the experimental results, by comparing them with those obtained for other bacterial species such as Proteus mirabilis and Bacillus subtilis.

Tokita, Rie; Katoh, Takaki; Maeda, Yusuke; Wakita, Jun-ichi; Sano, Masaki; Matsuyama, Tohey; Matsushita, Mitsugu

2009-07-01

454

Porin activity in the osmotic shock fluid of Escherichia coli.  

PubMed Central

Osmotic shock fluid of Escherichia coli exhibited pore-forming activity. This activity could be followed by an in vitro assay based on the conductivity increase for ions due to the presence of pores in black lipid membranes. The histogram (the distribution of conductivity increments in a single pore experiment) obtained with osmotic shock fluid from E. coli was identical to the histogram obtained by detergent-solubilized porin isolated from the outer membrane. The osmotic shock fluid from porin-negative mutants also exhibited pore activity, although the histogram and ion specificity were different from those of porin. Antibodies raised against detergent-solubilized porin were able to form precipitin lines by the Ouchterlony immunodiffusion technique when shock fluids, but not detergent-solubilized porin, were used. These antibodies prevented the formation of pores when shock fluids contained porin but not when shock fluids obtained from porin-negative mutants were used. Macroscopic membrane conductivity of shock fluids due to porin exhibited a concentration dependence, in contrast to detergent-solubilized porin. These results indicate that the hydrodynamic properties of periplasmic or "soluble" porin are different from those of the detergent-solubilized porin of the outer membrane. Periplasmic porin comprises about 0.7% of total protein in the osmotic shock fluid. Images PMID:357415

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

1978-01-01

455

Release Factor One Is Nonessential in Escherichia coli  

PubMed Central

Recoding a stop codon to an amino acid may afford orthogonal genetic systems for biosynthesizing new protein and organism properties. Although reassignment of stop codons has been found in extant organisms, a model organism is lacking to investigate the reassignment process and to direct code evolution. Complete reassignment of a stop codon is precluded by release factors (RFs), which recognize stop codons to terminate translation. Here we discovered that RF1 could be unconditionally knocked out from various Escherichia coli stains, demonstrating that the reportedly essential RF1 is generally dispensable for the E. coli species. The apparent essentiality of RF1 was found to be caused by the inefficiency of a mutant RF2 in terminating all UAA stop codons; a wild type RF2 was sufficient for RF1 knockout. The RF1-knockout strains were autonomous and unambiguously reassigned UAG to encode natural or unnatural amino acids (Uaas) at multiple sites, affording a previously unavailable model for studying code evolution and a unique host for exploiting Uaas to evolve new biological functions. PMID:22662873

2012-01-01

456

Enhanced Deletion Formation by Aberrant DNA Replication in Escherichia Coli  

PubMed Central

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

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

1997-01-01

457

Molybdenum cofactor negative mutants of Escherichia coli use citrate anaerobically.  

PubMed

Anaerobically, Escherichia coli cannot grow using either glycerol or citrate as sole carbon and energy source. However, it has been reported that a mixture of glycerol and citrate will support growth. We have found that wild-type strains of E. coli K-12 do not grow on glycerol plus citrate anaerobically. However, growth eventually occurs due to the frequent appearance of mutants. We found that such Cit+ mutants were defective in anaerobic respiration with nitrate or trimethylamine-N-oxide and were chlorate resistant (i.e. molybdenum cofactor deficient). Conversely, well characterized mutants in any of chlA, B, D, E, G and N were also able to use citrate anaerobically. No anaerobic growth differences between wild type and chl mutants were observed either with fermentable sugars or with glycerol plus fumarate or glycerol plus tartrate. Citrate lyase was induced anaerobically by citrate and repressed by glucose in both wild type strains and chl mutants. Furthermore, levels of citrate lyase, fumarate reductase, malate dehydrogenase, fumarase and alcohol dehydrogenase were similar in both types of strains under anaerobic conditions. It is conceivable that a functioning molybdenum cofactor prevents use of citrate by keeping citrate lyase in the inactive form. PMID:2182384

Clark, D P

1990-02-01

458

Partial purification of glycerophosphate acyltransferase from Escherichia coli.  

PubMed Central

Glycerophosphate acyltransferase, a membrane-bound enzyme catalyzing the initial step of phospholipid biosynthesis in Escherichia coli, has been extracted with Triton X-100, a nonionic detergent, and purified 20- to 40-fold. This preparation is free from lysophosphatidate acyltransferase. Glycerophosphate acyltransferase is inactive in detergent extracts, but can be reconstituted by the addition of phospholipid. Under such conditions, the enzyme is associated with phospholipid. The sole product of the reaction with acyl coenzyme A as substrate is 1-acyl-sn-glycero-3-phosphate. Furthermore, the enzyme shows a marked preference for saturated fatty acyl conenzyme A, implying that this enzyme is responsible for the predominance of saturated moieties in position 1 of E. coli phospholipids. Acyltransferase from two mutants, plsA and plsB, was partially purified and characterized. Results support the view that plsB is a structural gene for the acyltransferase, but suggest that the plsA gene product is not directly involved in phospholipid biosynthesis. PMID:324973

Snider, M D; Kennedy, E P

1977-01-01

459

Inorganic polyphosphates in the acquisition of competence in Escherichia coli.  

PubMed

A complex of polyhydroxybutyrate (PHB), Ca2+, and inorganic polyphosphate (polyP) was proposed as the membrane component responsible for competence for DNA entry in Escherichia coli (Reusch, R. N., and Sadoff, H. L. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 4176-4180). While chemical and immunological assays and 1H NMR have unequivocally established the identity and content of PHB in the complex, comparable methods were not available for polyP. With specific enzyme assays developed for polyP, we have identified, in chloroform extracts of competent cell membranes, a novel form of polyP of about 60 to 70 residues in a stoichiometric ratio of PHB to polyP of 2:1. In E. coli mutants, incapable of synthesizing the predominant, thousand-long polyP chains, appearance of this short polyP and its inclusion in membranes can account for their capacity to develop competence and indicates an auxiliary pathway for polyP synthesis. A variety of fluorescent lipid probes demonstrate the appearance of extensive rigid domains in membranes of competent cells. We propose that the PHB.Ca2+.polyP complex perturbs the conformation of the lipid matrix, making it more permeable to charged molecules and thus allowing the entry of DNA. PMID:7768888

Castuma, C E; Huang, R; Kornberg, A; Reusch, R N

1995-06-01

460

Characterization of the ferrous iron uptake system of Escherichia coli.  

PubMed Central

Escherichia coli has an iron(II) transport system (feo) which may make an important contribution to the iron supply of the cell under anaerobic conditions. Cloning and sequencing of the iron(II) transport genes revealed an open reading frame (feoA) possibly coding for a small protein with 75 amino acids and a membrane protein with 773 amino acids (feoB). The upstream region of feoAB contained a binding site for the regulatory protein Fur, which acts with iron(II) as a corepressor in all known iron transport systems of E. coli. In addition, a Fnr binding site was identified in the promoter region. The FeoB protein had an apparent molecular mass of 70 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was localized in the cytoplasmic membrane. The sequence revealed regions of homology to ATPases, which indicates that ferrous iron uptake may be ATP driven. FeoA or FeoB mutants could be complemented by clones with the feoA or feoB gene, respectively. Images PMID:8407793

Kammler, M; Schön, C; Hantke, K

1993-01-01

461

Recombinational Repair of DNA Damage in Escherichia coli and Bacteriophage ?  

PubMed Central

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

Kuzminov, Andrei

1999-01-01

462

Nutrient dependence of RNase E essentiality in Escherichia coli.  

PubMed

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

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

2013-03-01

463

Dissecting the roles of Escherichia coli hydrogenases in biohydrogen production.  

PubMed

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

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

2008-01-01

464

Photoreactivation of Escherichia coli is impaired at high growth temperatures.  

PubMed

Photolyase repairs UV-induced lesions in DNA using light energy, which is the principle of photoreactivation. Active photolyase contains the two-electron-reduced flavin cofactor. We observed that photoreactivation of Escherichia coli was impaired at growth temperatures ?37°C, and growth in this temperature range also resulted in decreased photolyase protein levels in the cells. However, the levels of phr transcripts (encoding photolyase) were almost unchanged at the various growth temperatures. A lacZ-reporter under transcriptional control of the phr promoter showed no temperature-dependent expression. However, a translational reporter consisting of the photolyase N-terminal ?/? domain-LacZ fusion protein exhibited lower ?-galactosidase activity at high growth temperatures (37-42°C). These results indicated that the change in photolyase levels at different growth temperatures is post-transcriptional in nature. Limited proteolysis identified several susceptible cleavage sites in E. coli photolyase. In vitro differential scanning calorimetry and activity assays revealed that denaturation of active photolyase occurs at temperatures ?37°C, while apo-photolyase unfolds at temperatures ?25°C. Evidence from temperature-shift experiments also implies that active photolyase is protected from thermal unfolding and proteolysis in vivo, even at 42°C. These results suggest that thermal unfolding and proteolysis of newly synthesized apo-photolyase, but not active photolyase, is responsible for the impaired photoreactivation at high growth temperatures (37-42°C). PMID:25839748

Xu, Lei; Tian, Changqing; Lu, Xiaohua; Ling, Liefeng; Lv, Jun; Wu, Mingcai; Zhu, Guoping

2015-06-01

465

Dissecting Escherichia coli Outer Membrane Biogenesis Using Differential Proteomics  

PubMed Central

The cell envelope of Gram-negative bacteria is a complex multi-layered structure comprising an inner cytoplasmic membrane and an additional asymmetric lipid bilayer, the outer membrane, which functions as a selective permeability barrier and is essential for viability. Lipopolysaccharide, an essential glycolipid located in the outer leaflet of the outer membrane, greatly contributes to the peculiar properties exhibited by the outer membrane. This complex molecule is transported to the cell surface by a molecular machine composed of seven essential proteins LptABCDEFG that form a transenvelope complex and function as a single device. While advances in understanding the mechanisms that govern the biogenesis of the cell envelope have been recently made, only few studies are available on how bacterial cells respond to severe envelope biogenesis defects on a global scale. Here we report the use of differential proteomics based on Multidimensional Protein Identification Technology (MudPIT) to investigate how Escherichia coli cells respond to a block of lipopolysaccharide transport to the outer membrane. We analysed the envelope proteome of a lptC conditional mutant grown under permissive and non permissive conditions and identified 123 proteins whose level is modulated upon LptC depletion. Most such proteins belong to pathways implicated in cell envelope biogenesis, peptidoglycan remodelling, cell division and protein folding. Overall these data contribute to our understanding on how E. coli cells respond to LPS transport defects to restore outer membrane functionality. PMID:24967819

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

2014-01-01

466

Improvements In Ethanologenic Escherichia Coli and Klebsiella Oxytoca  

SciTech Connect

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

Dr. David Nunn

2010-09-30

467

The Stress Response of Escherichia coli under Microgravity.  

NASA Astrophysics Data System (ADS)

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

Lynch, S.; Matin, A.

468

The fate of Escherichia coli and E. coli O157 in cattle slurry after application to land.  

PubMed

The fate of both faecal Escherichia coli and E. coli O157 in slurry following application to arable and grass plots on a clay loam soil was studied. Slurry (5% dry matter) containing 5.3 x 10(4) ml(-1) E. coli and 30 E. coli O157 100 ml(-1) was spread in early March. Initially, almost all E. coli were retained in the upper layers of the soil. Escherichia coli numbers steadily declined to less than 1% of those applied by day 29, and E. coli O157 were only detected in the soil and on the grass for the first week after application. There was some transport of bacteria to deeper layers of the soil, but this was approximately 2% of the total; transport to drains over the same period was mainly associated with rainfall events and amounted to approximately 7% of applied E. coli. However, there were indications that periods of heavy rainfall could cause significant losses of E. coli by both leaching and run-off. Experimental studies showed that E. coli O157 on grass, which was subsequently ensiled in conditions allowing aerobic spoilage, could multiply to numbers exceeding 10(6) g(-1) in the silage. PMID:10880190

Fenlon, D R; Ogden, I D; Vinten, A; Svoboda, I

2000-01-01

469

Improving Microbial Biogasoline Production in Escherichia coli Using Tolerance Engineering  

PubMed Central

ABSTRACT Engineering microbial hosts for the production of fungible fuels requires mitigation of limitations posed on the production capacity. One such limitation arises from the inherent toxicity of solvent-like biofuel compounds to production strains, such as Escherichia coli. Here we show the importance of host engineering for the production of short-chain alcohols by studying the overexpression of genes upregulated in response to exogenous isopentenol. Using systems biology data, we selected 40 genes that were upregulated following isopentenol exposure and subsequently overexpressed them in E. coli. Overexpression of several of these candidates improved tolerance to exogenously added isopentenol. Genes conferring isopentenol tolerance phenotypes belonged to diverse functional groups, such as oxidative stress response (soxS, fpr, and nrdH), general stress response (metR, yqhD, and gidB), heat shock-related response (ibpA), and transport (mdlB). To determine if these genes could also improve isopentenol production, we coexpressed the tolerance-enhancing genes individually with an isopentenol production pathway. Our data show that expression of 6 of the 8 candidates improved the production of isopentenol in E. coli, with the methionine biosynthesis regulator MetR improving the titer for isopentenol production by 55%. Additionally, expression of MdlB, an ABC transporter, facilitated a 12% improvement in isopentenol production. To our knowledge, MdlB is the first example of a transporter that can be used to improve production of a short-chain alcohol and provides a valuable new avenue for host engineering in biogasoline production. PMID:25370492

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

2014-01-01

470

Response of Escherichia coli growth rate to osmotic shock  

PubMed Central

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

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

2014-01-01

471

Response of Escherichia coli growth rate to osmotic shock.  

PubMed

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

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

2014-05-27

472

Bactericidal Activity of Human Eosinophilic Granulocytes against Escherichia coli  

PubMed Central

Eosinophils participate in allergic inflammation and may have roles in the body's defense against helminthic infestation. Even under noninflammatory conditions, eosinophils are present in the mucosa of the large intestine, where large numbers of gram-negative bacteria reside. Therefore, roles for eosinophils in host defenses against bacterial invasion are possible. In a system for bacterial viable counts, the bactericidal activity of eosinophils and the contribution of different cellular antibacterial systems against Escherichia coli were investigated. Eosinophils showed a rapid and efficient killing of E. coli under aerobic conditions, whereas under anaerobic conditions bacterial killing decreased dramatically. In addition, diphenylene iodonium chloride (DPI), an inhibitor of the NADPH oxidase and thereby of superoxide production, also significantly inhibited bacterial killing. The inhibitor of nitric oxide (NO) production l-N5-(1-iminoethyl)-ornithine dihydrochloride did not affect the killing efficiency, suggesting that NO or derivatives thereof are of minor importance under the experimental conditions used. To investigate the involvement of superoxide and eosinophil peroxidase (EPO) in bacterial killing, EPO was blocked by azide. The rate of E. coli killing decreased significantly in the presence of azide, whereas addition of DPI did not further decrease the killing, suggesting that superoxide acts in conjunction with EPO. Bactericidal activity was seen in eosinophil extracts containing granule proteins, indicating that oxygen-independent killing may be of importance as well. The findings suggest that eosinophils can participate in host defense against gram-negative bacterial invasion and that oxygen-dependent killing, i.e., superoxide acting in conjunction with EPO, may be the most important bactericidal effector function of these cells. PMID:11349018

Persson, Terese; Andersson, Pia; Bodelsson, Mikael; Laurell, Martin; Malm, Johan; Egesten, Arne

2001-01-01

473

Extensive Gene Diversity in Septicemic Escherichia coli Strains  

PubMed Central

Extraintestinal pathogenic Escherichia coli strains (ExPEC) are the cause of a diverse spectrum of invasive infections in humans and animals, and these infections often lead to septicemia. Strains of serogroups O2 and O78 of E. coli are involved in human urinary tract infections and newborn meningitis and also constitute the major serotypes involved in avian colisepticemia. In the present study we compared the unique genomic sequences of two such septicemic strains, strains O2-1772 and O78-9, obtained by suppression subtractive hybridization. Evaluation of the degree of similarity between these two strains, which cause the same disease, revealed a high degree of diversity, with only a few shared genes. Subsequently, additional strains of each serogroup of human and animal origin were screened by PCR, and the results provided further evidence for the existence of a high degree of genome plasticity. These results were unexpected, in view of data showing that the two O157:H7 strains that have been sequenced are nearly identical in terms of virulence factors. Furthermore, the data obtained for the septicemic strains suggest that each step in the infection can be mediated by a number of alternative virulence factors, indicating the existence of a mix-and-match combinatorial system. Although whole-genome comparisons of E. coli strains causing different diseases have shown great differences in gene contents, we show that such differences exist even within strains that cause the same disease and that target the same host tissues. Moreover, in addition to the high level of genome plasticity, we show that the large pool of virulence genes in the septicemic strains is independent of the host, implying a high degree of zoonotic risk. PMID:15634952

Mokady, Daphna; Gophna, Uri; Ron, Eliora Z.

2005-01-01

474

Mechanism for accommodation to cadmium exposure in Escherichia coli B  

SciTech Connect

All organisms possess, to varying degrees, the ability to adapt to changes in their environment. The extent of this capability can be the determining factor in whether or not an organism survives. The adaptation of the enteric microorganism, Escherichia coli, to the heavy metal cadmium is not the result of a beneficial mutation, and has been termed accommodation. A protein was found that binds to, and appears to be induced by cadmium. The work presented in this thesis is directed at (1) determining the mechanism of accommodation of E.coli to cadmium, and (2) determining the potential role of a putative cadmium binding-protein in accomplishing this accommodation. The presence of three chemically related cadmium-binding proteins, possessing molecular weights of 150,000, 67,000, and 38,000, respectively, was demonstrated. The cadmium-protein bond in the 150 and 67 kDa proteins was stable when boiled in sodium dodecyl sulfate, but was lost in the presence of reducing agents. Evidence was obtained which supported the assertion that the lower molecular weight cadmium-binding proteins were proteolytic or oxidative breakdown products of the larger cadmium-binding proteins. The loss of cadmium-binding activity was time dependent, and appeared to be accelerated by the presence of high salt. To determine if the process of accommodation involved the sequestration of cadmium in the outer cell surface, subcellular fractionation experiments were performed under a variety of post-exposure conditions. The possibility that the cell surface was rendered impermeable to cadmium ions during its recovery was also examined. Neither of these processes was found to be involved in the accommodative response. Indeed, the results of these studies support the concept that E.coli circumvents the presence of internal cadmium by converting it to a form that is no longer toxic to the cell.

Kitchen, J.R. Jr.

1989-01-01

475

Escherichia coli RNase R has dual activities, helicase and RNase.  

PubMed

In Escherichia coli, the cold shock response occurs when there is a temperature downshift from 37 degrees C to 15 degrees C, and this response is characterized by induction of several cold shock proteins, including the DEAD-box helicase CsdA, during the acclimation phase. CsdA is involved in a variety of cellular processes. Our previous studies showed that the helicase activity of CsdA is critical for its function in cold shock acclimation of cells and that the only proteins that were able to complement its function were another helicase, RhlE, an RNA chaperone, CspA, and a cold-inducible exoribonuclease, RNase R. Interestingly, other major 3'-to-5' processing exoribonucleases of E. coli, such as polynucleotide phosphorylase and RNase II, cannot complement the cold shock function of CsdA. Here we carried out a domain analysis of RNase R and showed that this protein has two distinct activities, RNase and helicase, which are independent of each other and are due to different domains. Mutant RNase R proteins that lack the RNase activity but exhibit the helicase activity were able to complement the cold shock function of CsdA, suggesting that only the helicase activity of RNase R is essential for complementation of the cold shock function of CsdA. We also observed that in vivo deletion of the two cold shock domains resulted in a loss of the ability of RNase R to complement the cold shock function of CsdA. We further demonstrated that RNase R exhibits helicase activity in vitro independent of its RNase activity. Our results shed light on the unique properties of RNase R and how it is distinct from other exoribonucleases in E. coli. PMID:20023028

Awano, Naoki; Rajagopal, Vaishnavi; Arbing, Mark; Patel, Smita; Hunt, John; Inouye, Masayori; Phadtare, Sangita

2010-03-01