Sample records for bioluminescent escherichia coli

  1. Generation of recombinant bioluminescent Escherichia coli for quantitative determination of bacterial adhesion.

    PubMed

    AlLuhaybi, Khalid Abdul Rahman; Alghaith, Ghadah Yazeed; Moneib, Nayera Ahmed; Yassien, Mahmoud Abdul Magead

    2015-07-01

    Bacterial adhesion to urinary catheter was evaluated by measuring the light emitted from a recombinant bioluminescent glycocalyx producer Escherichia coli strain. Generation of the bioluminescent strain was carried out by transforming the bacterial cells with pUCP18-GFP plasmid that contains a green fluorescence gene. Light emission measurement was closely correlated with the number of the adherent cells, giving a detectable signal from 1.2 X 102 cells. The efficiency of this assay was confirmed by testing the antiadherent effect of subinhibitory concentrations of ciprofloxacin with the aid of a model for in-vitro catheter colonization. There was no significant difference in the percentage reduction of adherent cells obtained by both light emission measurement and viable cell count techniques. PMID:26142520

  2. Assessment of Photodynamic Destruction of Escherichia coli O157:H7 and Listeria monocytogenes by Using ATP Bioluminescence

    PubMed Central

    Romanova, N. A.; Brovko, L. Y.; Moore, L.; Pometun, E.; Savitsky, A. P.; Ugarova, N. N.; Griffiths, M. W.

    2003-01-01

    Antimicrobial photodynamic therapy was shown to be effective against a wide range of bacterial cells, as well as for fungi, yeasts, and viruses. It was shown previously that photodestruction of yeast cells treated with photosensitizers resulted in cell destruction and leakage of ATP. Three photosensitizers were used in this study: tetra(N-methyl-4-pyridyl)porphine tetratosylate salt (TMPyP), toluidine blue O (TBO), and methylene blue trihydrate (MB). A microdilution method was used to determine MICs of the photosensitizers against both Escherichia coli O157:H7 and Listeria monocytogenes. To evaluate the effects of photodestruction on E. coli and L. monocytogenes cells, a bioluminescence method for detection of ATP leakage and a colony-forming assay were used. All tested photosensitizers were effective for photodynamic destruction of both bacteria. The effectiveness of photosensitizers (in microgram-per-milliliter equivalents) decreased in the order TBO > MB > TMPyP for both organisms. The MICs were two- to fourfold higher for E. coli O157:H7 than for L. monocytogenes. The primary effects of all of the photosensitizers tested on live bacterial cells were a decrease in intracellular ATP and an increase in extracellular ATP, accompanied by elimination of viable cells from the sample. The time courses of photodestruction and intracellular ATP leakage were different for E. coli and L. monocytogenes. These results show that bioluminescent ATP-metry can be used for investigation of the first stages of bacterial photodestruction. ? PMID:14602591

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

    PubMed

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

    2013-05-01

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

  4. 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....

  5. Escherichia Coli

    ERIC Educational Resources Information Center

    Goodsell, David S.

    2009-01-01

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

  6. Enterohemorrhagic Escherichia coli

    Microsoft Academic Search

    Stelios Viazis; Francisco Diez-Gonzalez

    2011-01-01

    Enterohemorrhagic Escherichia coli (EHEC) have been recognized as a cause of serious illness and mortality in outbreaks of foodborne illness that involve a large variety of foods. In general, most pathogenic strains behave biochemically and ecologically like any other nonpathogenic E. coli, making their detection among commensal E. coli an important problem, especially among EHEC. E. coli infections in humans

  7. Pathogenic Escherichia coli

    Microsoft Academic Search

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

    2004-01-01

    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,

  8. 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...

  9. Escherichia coli diarrhoea*

    PubMed Central

    1980-01-01

    In recent years it has become clear that three types of Escherichia coli—enterotoxigenic, enteropathogenic, and enteroinvasive—play important roles in the etiology of acute diarrhoea. This report reviews the available knowledge on the epidemiology, clinical features, and pathophysiology of acute diarrhoea caused by these three types of E. coli, summarizes information on their laboratory diagnosis, and outlines priorities for further research. Particular attention is paid to important aspects of the relationship between enterotoxigenic E. coli diarrhoea in young animals and in man, and to recent advances in the development of E. coli vaccines for use in animals and their potential relevance to the development of an E. coli vaccine for use in man. PMID:6991145

  10. 76 FR 20542 - Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-13

    ...beef, pork sausage, chicken, oysters, cheese, fresh mushrooms...it is not surprising that one study found Escherichia coli and coliphages...at retail markets. In this study, 10 purchases of each of the...chicken, fresh pork, fresh oyster, fresh mushrooms,...

  11. Escherichia coli proteomics and bioinformatics 

    E-print Network

    Niu, Lili

    2009-05-15

    of proteins, can be used to study the products of the genome and the physiology of Escherichia coli cells at different conditions. By comparing proteome from different growth phases, such as exponential and stationary phase, a lot of proteins with changes can...

  12. 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...

  13. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Escherichia coli serological reagents. 866...Serological Reagents § 866.3255 Escherichia coli serological reagents. (a) Identification. Escherichia coli serological reagents...

  14. 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...

  15. Bioluminescence.

    PubMed

    Wilson, T; Hastings, J W

    1998-01-01

    Bioluminescence has evolved independently many times; thus the responsible genes are unrelated in bacteria, unicellular algae, coelenterates, beetles, fishes, and others. Chemically, all involve exergonic reactions of molecular oxygen with different substrates (luciferins) and enzymes (luciferases), resulting in photons of visible light (approximately 50 kcal). In addition to the structure of luciferan, several factors determine the color of the emissions, such as the amino acid sequence of the luciferase (as in beetles, for example) or the presence of accessory proteins, notably GFP, discovered in coelenterates and now used as a reporter of gene expression and a cellular marker. The mechanisms used to control the intensity and kinetics of luminescence, often emitted as flashes, also vary. Bioluminescence is credited with the discovery of how some bacteria, luminous or not, sense their density and regulate specific genes by chemical communication, as in the fascinating example of symbiosis between luminous bacteria and squid. PMID:9891783

  16. Negative Chemotaxis in Escherichia coli

    PubMed Central

    Tso, Wung-Wai; Adler, Julius

    1974-01-01

    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

  17. Recombinant collagen production optimization in Escherichia coli

    E-print Network

    Whittemore, Brett A

    2005-01-01

    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 ...

  18. Engineering a Reduced Escherichia coli Genome

    Microsoft Academic Search

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

    2002-01-01

    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

  19. Strategies for Protein Overproduction in Escherichia coli.

    ERIC Educational Resources Information Center

    Mott, John E.

    1984-01-01

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

  20. Transcriptional proofreading in Escherichia coli.

    PubMed Central

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

    1989-01-01

    A novel transcriptional proofreading mechanism associated with the beta-subunit of wild-type RNA polymerase from Escherichia coli is suggested from the following data. The purified holoenzyme contains an NTPase activity which specifically converts noncognate NTPs to their corresponding NDP in a template-dependent manner during in vitro transcription of synthetic single- and double-stranded templates. In contrast, purified enzyme from an rpoB mutant which shows increased transcriptional error lacked template-dependent NTP hydrolytic activity. The NTP hydrolytic activity of wild-type enzyme was critically dependent on the integrity of the initiation complex, and required continued transcriptional elongation. Transcription and translation of the lacZ gene proceeded 17% faster in the mutant than in its wild-type parent. These results are discussed in terms of a proofreading model in which the rate of transcription is limited by proofreading events that involve recognition and hydrolysis of noncognate NTPs before they can be misincorporated into RNA. Images PMID:2555156

  1. Comparison of 61 Sequenced Escherichia coli Genomes

    Microsoft Academic Search

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

    2010-01-01

    Escherichia coli is an important component of the biosphere and is an ideal model for studies of processes involved in bacterial genome evolution.\\u000a 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\\u000a pan- and core genomes of this set of sequenced strains. A hierarchical

  2. Escherichia coli O157:H7

    Microsoft Academic Search

    Elaine D. Berry; James E. Wells

    2010-01-01

    Escherichia coli O157:H7 is a zoonotic pathogen that is an important cause of human foodborne and waterborne disease, with a spectrum of illnesses ranging from asymptomatic carriage and diarrhea to the sometimes fatal hemolytic uremic syndrome. Outbreaks of E. coli O157:H7 disease are often associated with undercooked beef, but there are other sources of transmission, including water, produce, and animal

  3. Pathogenic potential of escherichia coli O26 and sorbitol-fermenting escherichia coli O157:NM 

    E-print Network

    Rosser, Tracy

    2010-01-01

    Verocytotoxin-producing Escherichia coli (VTEC) are important human pathogens that may cause diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome (HUS). Worldwide, non-sorbitol-fermenting (NSF) VTEC O157:H7 is ...

  4. Inactivation of Escherichia coli by photocatalytic oxidation.

    PubMed

    Bekbölet, M; Araz, C V

    1996-03-01

    The inactivation of Escherichia coli (E.coli) was studied in presterilized surface water sample using titanium dioxide as the photocatalyst under irradiation of BLF Fluorescent lamps. Inactivation of E.coli (10(3) CFU/mL) was achieved in 60 min in the presence of 1.0 mg TiO2/mL. Photocatalytic inactivation data was evaluated in terms of first order rate equation N/N0 = e (-kIt). The reaction rate constant k, 1.22*10(-2)(mW min/cm2)-1 was calculated. PMID:8867143

  5. Influence of autoinducer 2 (ai-2) and ai-2-like inhibitors generated from ground beef on escherichia coli o157:h7 protein expression

    E-print Network

    Soni, Kamleshkumar A.

    2009-05-15

    contains compounds that can interfere with AI-2-mediated bioluminescence expression in Vibrio. harveyi. The underlying hypothesis of this work was that AI-2 molecules affect the protein expression in Escherichia coli O157:H7 and AI-2 inhibitory molecules...

  6. Functional motifs in Escherichia coli NC101.

    PubMed

    Motalleb, Gholamreza

    2013-01-01

    Escherichia coli (E. coli) bacteria can damage DNA of the gut lining cells and may encourage the development of colon cancer according to recent reports. Genetic switches are specific sequence motifs and many of them are drug targets. It is interesting to know motifs and their location in sequences. At the present study, Gibbs sampler algorithm was used in order to predict and find functional motifs in E. coli NC101 contig 1. The whole genomic sequence of Escherichia coli NC101 contig 1 were retrieved from http://www.ncbi.nlm.nih.gov (NCBI Reference sequence: NZ_AEFA01000001.1) in order to be analyzed with DAMBE software and BLAST. The results showed that the 6-mer motif is CUGGAA in most sequences (genes1-3, 8, 9, 12, 14-18, 20-23, 25, 27, 29, 31-34), CUUGUA for gene 4 , CUGUAA for gene 5, CUGAUG for gene 6, CUGAUA for gene7, CUGAAA for genes 10, 11, 13, 26, 28, and CUGGAG for gene 19, and CUGGUA for gene30 in E. coli NC101 contig 1. It is concluded that the 6-mer motif is CUGGAA in most sequences in E. coli NC101 contig1. The present study may help experimental studies on elucidating the pharmacological and phylogenic functions of the motifs in E. coli. PMID:24551810

  7. Escherichia Coli--Key to Modern Genetics.

    ERIC Educational Resources Information Center

    Bregegere, Francois

    1982-01-01

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

  8. Escherichia coli and Sudden Infant Death Syndrome

    PubMed Central

    Bettelheim, Karl A.; Goldwater, Paul N.

    2015-01-01

    This review examines the association of strains of Escherichia coli with sudden infant death syndrome (SIDS) and the possible role these bacteria play in this enigmatic condition. The review addresses evidence for E. coli in SIDS infants, potential sources of E. coli in the environment, colonization by commensal and pathogenic strains, the variety of currently accepted pathotypes, and how these pathotypes could compromise intestinal integrity and induce inflammation. Both intestinal and extraintestinal pathotypes are compared in relation to the apparent liability in which virulence traits can be gained or lost by strains of E. coli. The way in which E. coli infections fit with current views on infant sleeping position and other SIDS risk factors is highlighted.

  9. Survival of Escherichia coli in stormwater biofilters.

    PubMed

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

    2014-04-01

    Biofilters are widely adopted in Australia for stormwater treatment, but the reported removal of common faecal indicators (such as Escherichia coli (E. coli)) varies from net removal to net leaching. Currently, the underlying mechanisms that govern the faecal microbial removal in the biofilters are poorly understood. Therefore, it is important to study retention and subsequent survival of faecal microorganisms in the biofilters under different biofilter designs and operational characteristics. The current study investigates how E. coli survival is influenced by temperature, moisture content, sunlight exposure and presence of other microorganisms in filter media and top surface sediment. Soil samples were taken from two different biofilters to investigate E. coli survival under controlled laboratory conditions. Results revealed that the presence of other microorganisms and temperature are vital stressors which govern the survival of E. coli captured either in the top surface sediment or filter media, while sunlight exposure and moisture content are important for the survival of E. coli captured in the top surface sediment compared to that of the filter media. Moreover, increased survival was found in the filter media compared to the top sediment, and sand filter media was found be more hostile than loamy sand filter media towards E. coli survival. Results also suggest that the contribution from the tested environmental stressors on E. coli survival in biofilters will be greatly affected by the seasonality and may vary from one site to another. PMID:24371007

  10. Escherichia coli in retail processed food.

    PubMed Central

    Pinegar, J. A.; Cooke, E. M.

    1985-01-01

    Four thousand two hundred and forty six samples of retail processed food were examined for the presence of Escherichia coli. Overall 12% of samples contained this organism, cakes and confectionery being more frequently contaminated (28%) than meat and meat based products (9%). Contamination was more frequent in the summer months than in the colder weather and 27% of the contaminated foods contained greater than 10(3) E. coli/g. E. coli from meat and meat based products were more commonly resistant to one or more antibiotics (14%) than were confectionery strains (1%). The significance of these findings in relation to the E. coli population of the human bowel is discussed. PMID:3894508

  11. Biosynthesis of 4-aminobenzoate in Escherichia coli.

    PubMed

    Huang, M; Gibson, F

    1970-06-01

    Two different mutations (pabA and pabB) affecting 4-aminobenzoate biosynthesis were obtained in strains of Escherichia coli lacking chorismate mutase and anthranilate synthetase activity, thus allowing study of the pathway of biosynthesis of 4-aminobenzoate by use of cell extracts of strains carrying the pab mutations. Two components with approximate molecular weights of 9,000 (component A) and 48,000 (component B) are concerned in the biosynthesis of 4-aminobenzoate from chorismate by E. coli. No diffusible intermediate compound could be detected. PMID:4914080

  12. Properties of an Escherichia coli cytotoxin.

    PubMed Central

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

    1978-01-01

    Isoelectric focusing of a heat-labile cytotoxin of Escherichia coli H30 revealed the presence of two molecular variants, pI 7.2 and a comparatively small quantity of pI 6.8. Predominant component pI 7.2 had a molecular weight of 28,000, induced some fluid accumulation in rabbit ileal loops, and showed no morphological response in Y-1 cells but a strong cytotoxic effect on Vero cells. PMID:208977

  13. Systematic Mutagenesis of the Escherichia coli Genome

    Microsoft Academic Search

    Yisheng Kang; Tim Durfee; Jeremy D. Glasner; Yu Qiu; David Frisch; Kelly M. Winterberg; Frederick R. Blattner

    2004-01-01

    A high-throughput method has been developed for the systematic mutagenesis of the Escherichia coli genome. The system is based on in vitro transposition of a modified Tn5 element, the Sce-poson, into linear fragments of each open reading frame. The transposon introduces both positive (kanamycin resistance) and negative (I-SceI recognition site) selectable markers for isolation of mutants and subsequent allele replacement,

  14. Characteristics of verotoxigenic Escherichia coli from pigs.

    PubMed Central

    Gannon, V P; Gyles, C L; Friendship, R W

    1988-01-01

    Porcine verotoxigenic Escherichia coli were characterized with respect to frequency of occurrence, serogroup, and association with disease, weaning, and selected properties of the bacterium. Of 668 strains of E. coli from southern Ontario pigs with enteric disease, 32 (4.8%) produced verotoxin at 10(3)-10(7) cytotoxic doses per mL of culture supernatant. Of 22 isolates which belonged to O serogroups 138, 139 and 141, 15 produced verotoxin. Among other enterotoxigenic types of E. coli, two of 57 isolates of O157:K"V17" and two of 96 isolates of O149:K91 were verotoxigenic. The remaining 13 verotoxigenic E. coli belonged to O groups 2, 107, 120, 121 and 130. An additional 21 verotoxigenic E. coli belonging to O groups 138, 139 and 141 and three to O157:K"V17" were identified in a collection of 47 E. coli recovered from weaned pigs with enteric disease. Verotoxigenic E. coli were associated with postweaning diarrhea, bloody stools, sudden death and edema disease. They were isolated at similar frequencies (14%) from healthy weaned pigs, and from weaned pigs with enteric disease. Isolation rates from neonates were low and significantly different from rates in weaned pigs. Neutralizing antibody to verotoxin was not detected in the sera of 45 pigs, which included pigs from herds with a history of edema disease. Verotoxin was not associated with production of colicin, hemolysin, or enterotoxins or with any of 23 biochemical properties of the organisms. The serological data indicate that porcine verotoxigenic E. coli are not a common source of verotoxigenic E. coli for humans. Porcine verotoxin may play a role in postweaning diarrhea and absence of detectable neutralizing antibody in serum may be an important aspect of pathogenesis. PMID:3048621

  15. Thymineless Death in Escherichia coli: Strain Specificity

    PubMed Central

    Cummings, Donald J.; Mondale, Lee

    1967-01-01

    Thymineless death of various ultraviolet (UV)-sensitive strains of Escherichia coli B and K-12 was investigated. It was found that E. coli B, Bs?12, K-12 rec-21, and possibly K-12 Lon?, all sensitive to UV, were also sensitive to thymine starvation. However, other UV-sensitive strains of E. coli were found to display the typical resistant-type kinetics of thymineless death. The correlation of these results with various other cellular processes suggested that the filament-forming ability of the bacteria might be involved in the mechanism of thymineless death. It was apparent from the present results that capacity for host-cell reactivation, recombination ability, thymine dimer excision, and probably induction of a defective prophage had little to do with determining sensitivity to thymine deprivation. Images PMID:5337772

  16. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 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....

  17. 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...

  18. Original article Resistance of Escherichia coli growing as biofilms

    E-print Network

    Boyer, Edmond

    Original article Resistance of Escherichia coli growing as biofilms to disinfectants C Ntsama) Summary ― The bactericidal activity of various disinfectants (cationic or amphoteric surfactants, oxidizing agents, phenolic derivatives) was determined against E.scherichin coli CIP 54127 obtained

  19. Survival of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi in Vembanadu

    E-print Network

    Mazumder, Asit

    Survival of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi the survival response of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi- otypes of Escherichia coli, Salmonella enterica typhi and paratyphi are highly endemic to India

  20. Carbon nutrition of Escherichia coli in the mouse intestine

    E-print Network

    Conway, Tyrrell

    used by E. coli MG1655 to colonize, having an impact on both the initiation and maintenance stages. N > ribose. The results of this systematic analysis of nutrients used by E. coli MG1655 to colonize the mouse E. coli pathogens in some individuals and a barrier to infection in others. Escherichia coli

  1. Automatic Tracking of Escherichia Coli Bacteria , Shahid Khan2 3

    E-print Network

    Central Florida, University of

    bacteria (E. coli), which can generally cause several intestinal and extra-intestinal infections of Escherichia Coli Bacteria 825 Fig. 1. (Left) A typical view of E. coli bacteria under a phase may appear as a white bulb (B). (Right) An sequence of E. coli bacteria. Among the efforts devoted

  2. Core and panmetabolism in Escherichia coli.

    PubMed

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

    2011-03-01

    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

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

    EPA Science Inventory

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

  4. S-Nitrosylation Signaling in Escherichia coli

    NSDL National Science Digital Library

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

    2012-06-12

    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.

  5. Engineering Desiccation Tolerance in Escherichia coli

    PubMed Central

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

    2000-01-01

    Recombinant sucrose-6-phosphate synthase (SpsA) was synthesized in Escherichia coli BL21DE3 by using the spsA gene of the cyanobacterium Synechocystis sp. strain PCC 6803. Transformants exhibited a 10,000-fold increase in survival compared to wild-type cells following either freeze-drying, air drying, or desiccation over phosphorus pentoxide. The phase transition temperatures and vibration frequencies (P?O stretch) in phospholipids suggested that sucrose maintained membrane fluidity during cell dehydration. PMID:10742260

  6. Regulation of glutaminase levels in Escherichia coli.

    PubMed Central

    Prusiner, S

    1975-01-01

    Nitrogenous metabolites, cyclic adenosine 3':5'-monophosphate (cAMP), and the stage of culture growth all influence the levels of glutaminase A in Escherichia coli, but no variables in culture conditions alter the levels of glutaminase B. Growth of E. coli on culture media containing glucose and excess ammonia results in a rise in the level of glutaminase A as the cultures enter stationary phase; this rise is abolished by ammonia limitation. cAMP or glycerol reduce the level of glutaminase A. In mutants deficient in cAMP receptor protein, glutaminase A levels are unchanged by cAMP, but they are still susceptible to regulation by ammonia. We consider glutaminase B to be a constitutive enzyme, since its levels appear independent of nutritional conditions. PMID:239927

  7. Escherichia coli growth under modeled reduced gravity

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  8. Engineering the Escherichia coli Fermentative Metabolism

    NASA Astrophysics Data System (ADS)

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

    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.

  9. Transient fluorescence in synchronously dividing Escherichia coli.

    PubMed Central

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

    1985-01-01

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

  10. Amino Sugar Assimilation by Escherichia coli

    PubMed Central

    Rolls, James P.; Shuster, C. W.

    1972-01-01

    The carbon skeleton of glucose is extensively randomized during conversion to cell wall glucosamine by Escherichia coli K-12. Exogenous glucosamine-1-14C is selectively oxidized, and isotope incorporation into cellular glucosamine is greatly diluted during assimilation. A mutant unable to grow with N-acetylglucosamine as a carbon and energy source was isolated from E. coli K-12. This mutant was found to be defective in glucosamine-6-phosphate deaminase. Glucosamine-1-14C and N-acetylglucosamine-1-14C were assimilated during the growth of mutant cultures without degradation or carbon randomization. Assimilated isotopic carbon resided entirely in cell wall glucosamine and muramic acid. Some isotope dilution occurred from biosynthesis, but at high concentrations (0.2 mm) of added N-acetylglucosamine nearly all cellular amino sugar was derived from the exogenous source. Growth of the mutant was inhibited with 1 mmN-acetylglucosamine. PMID:4563983

  11. Kefir grain tolerance to Escherichia coli contamination--industrial advantages

    E-print Network

    Paris-Sud XI, Université de

    NOTE Kefir grain tolerance to Escherichia coli contamination--industrial advantages Piotr / Published online: 21 August 2012 # INRA and Springer-Verlag, France 2012 Abstract Kefir grains are used the possibility of the re-use of kefir grains grown at 18 °C for 24 h in pasteurized Escherichia coli contaminated

  12. Complete Genome Sequence of Uropathogenic Escherichia coli Strain CI5.

    PubMed

    Mehershahi, Kurosh S; Abraham, Soman N; Chen, Swaine L

    2015-01-01

    Escherichia coli represents the primary etiological agent responsible for urinary tract infections, one of the most common infections in humans. We report here the complete genome sequence of uropathogenic Escherichia coli strain CI5, a clinical pyelonephritis isolate used for studying pathogenesis. PMID:26021932

  13. Research Note--Prevalence of Pathogenic Escherichia coli in the

    E-print Network

    Singer, Randall

    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 in the environment. Isolates were collected from six broiler flocks representing six geographically disparate ranches

  14. Complete Genome Sequence of Uropathogenic Escherichia coli Strain CI5

    PubMed Central

    Mehershahi, Kurosh S.; Abraham, Soman N.

    2015-01-01

    Escherichia coli represents the primary etiological agent responsible for urinary tract infections, one of the most common infections in humans. We report here the complete genome sequence of uropathogenic Escherichia coli strain CI5, a clinical pyelonephritis isolate used for studying pathogenesis. PMID:26021932

  15. Chemical Organizations in the Central Sugar Metabolism of Escherichia Coli

    E-print Network

    Dittrich, Peter

    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

  16. Transport proteins promoting Escherichia coli pathogenesis

    PubMed Central

    Tang, Fengyi; Saier, Milton H.

    2014-01-01

    Escherichia coli is a genetically diverse species infecting hundreds of millions of people worldwide annually. We examined seven well-characterized E. coli pathogens causing urinary tract infections, gastroenteritis, pyelonephritis and haemorrhagic colitis. Their transport proteins were identified and compared with each other and a non-pathogenic E. coli K12 strain to identify transport proteins related to pathogenesis. Each pathogen possesses a unique set of protein secretion systems for export to the cell surface or for injecting effector proteins into host cells. Pathogens have increased numbers of iron siderophore receptors and ABC iron uptake transporters, but the numbers and types of low-affinity secondary iron carriers were uniform in all strains. The presence of outer membrane iron complex receptors and high-affinity ABC iron uptake systems correlated, suggesting co-evolution. Each pathovar encodes a different set of pore-forming toxins and virulence-related outer membrane proteins lacking in K12. Intracellular pathogens proved to have a characteristically distinctive set of nutrient uptake porters, different from those of extracellular pathogens. The results presented in this report provide information about transport systems relevant to various types of E. coli pathogenesis that can be exploited in future basic and applied studies. PMID:24747185

  17. Ancestral Lineages of Human Enterotoxigenic Escherichia coli? †

    PubMed Central

    Steinsland, Hans; Lacher, David W.; Sommerfelt, Halvor; Whittam, Thomas S.

    2010-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a common cause of diarrhea among children living in and among travelers visiting developing countries. Human ETEC strains represent an epidemiologically and phenotypically diverse group of pathogens, and there is a need to identify natural groupings of these organisms that may help to explain this diversity. Here, we sought to identify most of the important human ETEC lineages that exist in the E. coli population, because strains that originate from the same lineage may also have inherited many of the same epidemiological and phenotypic traits. We performed multilocus sequence typing (MLST) on 1,019 ETEC isolates obtained from humans in different countries and analyzed the data against a backdrop of MLST data from 1,250 non-ETEC E. coli and eight ETEC isolates from pigs. A total of 42 different lineages were identified, 15 of which, representing 792 (78%) of the strains, were estimated to have emerged >900 years ago. Twenty of the lineages were represented in more than one country. There was evidence of extensive exchange of enterotoxin and colonization factor genes between different lineages. Human and porcine ETEC have probably emerged from the same ancestral ETEC lineage on at least three occasions. Our findings suggest that most ETEC strains circulating in the human population today originate from well-established, globally widespread ETEC lineages. Some of the more important lineages identified here may represent a smaller and more manageable target for the ongoing efforts to develop effective ETEC vaccines. PMID:20534806

  18. Regulation of alcohol fermentation by Escherichia coli

    SciTech Connect

    Clark, D.P.

    1990-01-01

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

  19. Long term effects of Escherichia coli mastitis.

    PubMed

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

    2014-07-01

    Escherichia coli is one of the most frequently diagnosed causes of bovine mastitis, and is typically associated with acute, clinical mastitis. The objective of the present study was to evaluate the long term effects of intramammary infections by E. coli on milk yield and quality, especially milk coagulation. Twenty-four Israeli Holstein cows diagnosed with clinical mastitis due to intramammary infection by E. coli were used in this study. Mean lactation number, days in milk (DIM) and daily milk yield (DMY) at the time of infection was 3.3 ± 1.3, 131.7 days ± 78.6 and 45.7 L ± 8.4, respectively. DMY, milk constituents, somatic cells count (SCC), differential leukocytes count and coagulation parameters were subsequently assessed. Two patterns of inflammation were identified: 'short inflammation', characterized by <15% decrease in DMY and <30 days until return to normal (n?=?5), and 'long inflammation', characterized by >15% decrease in DMY and >30 days to reach a new maximum DMY (n = 19). The estimated mean loss of marketable milk during the study was 200 L/cow for 'short inflammation' cases, and 1,500 L/cow for 'long inflammation' ones. Significant differences between 'short' and 'long inflammation' effects were found in almost all parameters studied. Long-term detrimental effects on milk quality were found regardless of clinical or bacteriological cure of affected glands. PMID:24906501

  20. Efficient production of indigoidine in Escherichia coli.

    PubMed

    Xu, Fuchao; Gage, David; Zhan, Jixun

    2015-08-01

    Indigoidine is a bacterial natural product with antioxidant and antimicrobial activities. Its bright blue color resembles the industrial dye indigo, thus representing a new natural blue dye that may find uses in industry. In our previous study, an indigoidine synthetase Sc-IndC and an associated helper protein Sc-IndB were identified from Streptomyces chromofuscus ATCC 49982 and successfully expressed in Escherichia coli BAP1 to produce the blue pigment at 3.93 g/l. To further improve the production of indigoidine, in this work, the direct biosynthetic precursor L-glutamine was fed into the fermentation broth of the engineered E. coli strain harboring Sc-IndC and Sc-IndB. The highest titer of indigoidine reached 8.81 ± 0.21 g/l at 1.46 g/l L-glutamine. Given the relatively high price of L-glutamine, a metabolic engineering technique was used to directly enhance the in situ supply of this precursor. A glutamine synthetase gene (glnA) was amplified from E. coli and co-expressed with Sc-indC and Sc-indB in E. coli BAP1, leading to the production of indigoidine at 5.75 ± 0.09 g/l. Because a nitrogen source is required for amino acid biosynthesis, we then tested the effect of different nitrogen-containing salts on the supply of L-glutamine and subsequent indigoidine production. Among the four tested salts including (NH4)2SO4, NH4Cl, (NH4)2HPO4 and KNO3, (NH4)2HPO4 showed the best effect on improving the titer of indigoidine. Different concentrations of (NH4)2HPO4 were added to the fermentation broths of E. coli BAP1/Sc-IndC+Sc-IndB+GlnA, and the titer reached the highest (7.08 ± 0.11 g/l) at 2.5 mM (NH4)2HPO4. This work provides two efficient methods for the production of this promising blue pigment in E. coli. PMID:26109508

  1. Eco Cyc: encyclopedia of Escherichia coli genes and metabolism

    Microsoft Academic Search

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

    1999-01-01

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

  2. Animal models of enteroaggregative Escherichia coli infection

    PubMed Central

    Philipson, Casandra W.; Bassaganya-Riera, Josep; Hontecillas, Raquel

    2013-01-01

    Enteroaggregative Escherichia coli (EAEC) has been acknowledged as an emerging cause of gastroenteritis worldwide for over two decades. Epidemiologists are revealing the role of EAEC in diarrheal outbreaks as a more common occurrence than ever suggested before. EAEC induced diarrhea is most commonly associated with travelers, children and immunocompromised individuals however its afflictions are not limited to any particular demographic. Many attributes have been discovered and characterized surrounding the capability of EAEC to provoke a potent pro-inflammatory immune response, however cellular and molecular mechanisms underlying initiation, progression and outcomes are largely unknown. This limited understanding can be attributed to heterogeneity in strains and the lack of adequate animal models. This review aims to summarize current knowledge about EAEC etiology, pathogenesis and clinical manifestation. Additionally, current animal models and their limitations will be discussed along with the value of applying systems-wide approaches such as computational modeling to study host-EAEC interactions. PMID:23680797

  3. Enteropathogenic Escherichia coli: foe or innocent bystander?

    PubMed

    Hu, J; Torres, A G

    2015-08-01

    Enteropathogenic Escherichia coli (EPEC) remain one the most important pathogens infecting children and they are one of the main causes of persistent diarrhoea worldwide. Historically, typical EPEC (tEPEC), defined as those isolates with the attaching and effacement (A/E) genotype (eae(+)), which possess bfpA(+) and lack the stx(-) genes are found strongly associated with diarrhoeal cases. However, occurrence of atypical EPEC (aEPEC; eae(+)bfpA(-)stx(-)) in diarrhoeal and asymptomatic hosts has made investigators question the role of these pathogens in human disease. Current epidemiological data are helping to answer the question of whether EPEC is mainly a foe or an innocent bystander during infection. PMID:25726041

  4. Translocation of ?-Synuclein Expressed in Escherichia coli?

    PubMed Central

    Ren, Guoping; Wang, Xi; Hao, Shufeng; Hu, Hongyu; Wang, Chih-chen

    2007-01-01

    ?-Synuclein is a major component of Lewy bodies in Parkinson's disease. Although no signal sequence is apparent, ?-synuclein expressed in Escherichia coli is mostly located in the periplasm. The possibilities that ?-synuclein translocated into the periplasm across the inner membrane by the SecA or the Tat targeting route identified in bacteria and that ?-synuclein was released through MscL were excluded. The signal recognition particle-dependent pathway is involved in the translocation of ?-synuclein. The C-terminal 99-to-140 portion of the ?-synuclein molecule plays a signal-like role for its translocation into the periplasm, cooperating with the central 61-to-95 section. The N-terminal 1-to-60 region is not required for this translocation. PMID:17277073

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

    PubMed

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

    2014-08-01

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

  6. Chemotaxis toward sugars in Escherichia coli.

    PubMed

    Adler, J; Hazelbauer, G L; Dahl, M M

    1973-09-01

    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-beta-d-galactoside, galactitol, d-galactose, d-glucosamine, d-glucose, alpha-d-glucose-1-phosphate, lactose, maltose, d-mannitol, d-mannose, methyl-beta-d-galactoside, methyl-beta-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

  7. Characterization of enterotoxigenic bovine Escherichia coli.

    PubMed Central

    Sivaswamy, G; Gyles, C L

    1976-01-01

    Among 300 isolates of bovine Escherichia coli, 56 which had been found enterotoxigenic in calf gut loops were characterized on the basis of O and K antigens, colonial morphology and resistance to seven antimicrobial drugs. The 56 isolates enterotoxigenic in the calf were compared with the nonenterotoxigenic ones. Of the 56 enterotoxigenic E. coli the majority possessed the A type of K antigen and had OK groups, O9:K(PS274) or O101:K(RVC118). Fourteen of these isolates had the K99 antigen. None of 27 isolates found enterotoxigenic in the piglet but not in the calf possessed the K99 antigen or belonged to OK groups O9:K(PS274) or O101:K(RVC118). Comparison of the patterns of resistance to seven antimicrobial drugs showed that all enterotoxigenic and nonenterotoxigenic isolates were susceptible to nitrofurantoin and sulphachlorphyridiazine and that there was no significant difference in the patterns between the two groups. The majority of enterotoxigenic isolates were mucoid, whereas most of the nonenterotoxigenic isolates were nonmucoid. PMID:793694

  8. Nucleotide excision repair in Escherichia coli.

    PubMed Central

    Van Houten, B

    1990-01-01

    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

  9. Genes under positive selection in Escherichia coli

    PubMed Central

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

    2007-01-01

    We used a comparative genomics approach to identify genes that are under positive selection in six strains of Escherichia coli and Shigella flexneri, including five strains that are human pathogens. We find that positive selection targets a wide range of different functions in the E. coli genome, including cell surface proteins such as beta barrel porins, presumably because of the involvement of these genes in evolutionary arms races with other bacteria, phages, and/or the host immune system. Structural mapping of positively selected sites on trans-membrane beta barrel porins reveals that the residues under positive selection occur almost exclusively in the extracellular region of the proteins that are enriched with sites known to be targets of phages, colicins, or the host immune system. More surprisingly, we also find a number of other categories of genes that show very strong evidence for positive selection, such as the enigmatic rhs elements and transposases. Based on structural evidence, we hypothesize that the selection acting on transposases is related to the genomic conflict between transposable elements and the host genome. PMID:17675366

  10. Surface Expression of ?-Transaminase in Escherichia coli

    PubMed Central

    Gustavsson, Martin; Muraleedharan, Madhu Nair

    2014-01-01

    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

  11. Chemotaxis Toward Sugars in Escherichia coli

    PubMed Central

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

    1973-01-01

    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

  12. Expanding ester biosynthesis in Escherichia coli.

    PubMed

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

    2014-04-01

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

  13. The extracellular RNA complement of Escherichia coli

    PubMed Central

    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

    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

  14. Regulation of type III secretion in enterohaemorrhagic Escherichia coli 

    E-print Network

    Xu, Xuefang

    2011-11-25

    Enterohaemorrhagic Escherichia coli (EHEC) strains are associated with gastrointestinal and severe systemic disease in humans. EHEC O157:H7 is the most common serotype causing human infections in North America and the ...

  15. 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...

  16. Cleaving Yeast and Escherichia coli Genomes at a Single Site

    Microsoft Academic Search

    Michael Koob; Waclaw Szybalski

    1990-01-01

    The 15-megabase pair Saccharomyces cerevisiae and the 4.7-megabase pair Escherichia coli genomes were completely cleaved at a single predetermined site by means of the Achilles' heel cleavage (AC) procedure. The symmetric lac operator (lacO_s) was introduced into the circular Escherichia coli genome and into one of the 16 yeast chromosomes. Intact chromosomes from the resulting strains were prepared in agarose

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

    PubMed Central

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

    2014-01-01

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

  18. EXPERIMENTAL ESCHERICHIA COLI DIARRHOEA IN COLOSTRUM DEPRIVED LAMBS

    E-print Network

    Boyer, Edmond

    EXPERIMENTAL ESCHERICHIA COLI DIARRHOEA IN COLOSTRUM DEPRIVED LAMBS Marion DUCHET-SUCHAUX, AnneCHlA COLl CHEZ DES AGNEAUX PRIVÉS DE COLOSTRUM. ― Vingt agneaux (10 Berrichons du Cher et 10 Préalpes) élevés conventionnellement sans colostrum ont été inoculés par voie orale avec 1,7 à 3,1 x 108 E. coli B

  19. Expression of Treponema pallidum antigens in Escherichia coli K-12.

    PubMed Central

    Stamm, L V; Folds, J D; Bassford, P J

    1982-01-01

    A colony bank of recombinant plasmids harboring Treponema pallidum DNA inserts has been established in Escherichia coli K-12. By using an in situ immunoassay, we identified four E. coli clones that expressed T. pallidum antigens. Thus, recombinant DNA technology may provide powerful new tools for studying the pathogenesis of T. pallidum infection. Images FIG. 1 FIG. 2 FIG. 3 PMID:7047395

  20. Antibacterial Effect of Herbs and Spices Extract on Escherichia coli

    Microsoft Academic Search

    Venugopal Amrita; Dasani Sonal; Rai Shalini

    2009-01-01

    Escherichia coli are the most commonly present bacterium in the human intestine, which helps in preventing the entry of pathogenic microorganisms. E. coli are non-pathogenic in normal conditions, but if present in excess, will become causative agent of various diseases like urinary tract infection, diarrhoea, vomiting etc. With increasing resistance of microorganisms to antibiotics, there is a shift of choice

  1. Detection of Escherichia coli and Salmonella in chicken rinse carcasses

    Microsoft Academic Search

    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

    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.

  2. 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...

  3. EFFECT OF MANURE ON ESCHERICHIA COLI ATTACHMENT TO SOIL FRACTIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. Molecular Serotyping of Escherichia coli O111:H8

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate Escherichia coli serotyping is critical for pathogen diagnosis and surveillance of non-O157 shiga-toxigenic strains, however, few laboratories have this capacity. The molecular serotyping protocol described in this paper targets the somatic and flagellar antigens of E. coli O111:H8 used in...

  5. Genetic studies of the ribosomal proteins in Escherichia coli

    Microsoft Academic Search

    Renkichi Takata

    1972-01-01

    Ribosomal protein compositions of Serratia marcescens and Escherichia coli K12 were analyzed by using carboxymethyl cellulose column chromatography. Nine 50S and nine 30S ribosomal proteins of E. coli K12 could be distinguished from those of S. marcescens on the chromatogram.

  6. ATTACHMENT OF MANURE-BORNE ESCHERICHIA COLI TO SOIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Attachment of bacteria to soil is an important component of the bacteria fate and transport. Escherichia coli is commonly used as an indicator of fecal contamination in the environment. Despite the fact that E. coli are derived exclusively from feces or manure, effect of the presence of manure collo...

  7. Phylogenetic and genomic diversity of human bacteremic Escherichia coli strains

    Microsoft Academic Search

    Françoise Jaureguy; Luce Landraud; Virginie Passet; Laure Diancourt; Eric Frapy; Ghislaine Guigon; Etienne Carbonnelle; Olivier Lortholary; Olivier Clermont; Erick Denamur; Bertrand Picard; Xavier Nassif; Sylvain Brisse

    2008-01-01

    BACKGROUND: Extraintestinal pathogenic Escherichia coli (ExPEC) strains represent a huge public health burden. Knowledge of their clonal diversity and of the association of clones with genomic content and clinical features is a prerequisite to recognize strains with a high invasive potential. In order to provide an unbiased view of the diversity of E. coli strains responsible for bacteremia, we studied

  8. Molecular Serotyping of Escherichia coli O26:H11

    PubMed Central

    Durso, Lisa M.; Bono, James L.; Keen, James E.

    2005-01-01

    Serotyping is the foundation of pathogenic Escherichia coli diagnostics; however, few laboratories have this capacity. We developed a molecular serotyping protocol that targets, genetically, the same somatic and flagellar antigens of E. coli O26:H11 used in traditional serotyping. It correctly serotypes strains untypeable by traditional methods, affording primary laboratories serotyping capabilities. PMID:16085902

  9. Escherichia coli Response to Exogenous Pyrophosphate and Analogs

    Microsoft Academic Search

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

    2003-01-01

    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

  10. Influence of Escherichia coli hydrogenases on hydrogen fermentation from glycerol

    E-print Network

    Wood, Thomas K.

    , we evaluated the effect of inactivation of each E. coli hydrogenase on cell growth, hydrogen production, but no significant effect occurred at pH 6.5 or in complex medium. Inactivation of hydrogenase 3Influence of Escherichia coli hydrogenases on hydrogen fermentation from glycerol Viviana Sanchez

  11. Genome organisation and chromatin structure in Escherichia coli

    Microsoft Academic Search

    David Ussery; Thomas Schou Larsen; K. Trevor Wilkes; Carsten Friis; Peder Worning; Anders Krogh; Søren Brunak

    2001-01-01

    We have analysed the complete sequence of the Escherichia coli K12 isolate MG1655 genome for chromatin-associated protein binding sites, and compared the predicted location of predicted sites with experimental expression data from ‘DNA chip’ experiments. Of the dozen proteins associated with chromatin in E. coli, only three have been shown to have significant binding preferences: integration host factor (IHF) has

  12. Purification and Refolding of Cyclodextrin Glycosyltransferase Expressed Escherichia coli

    Microsoft Academic Search

    Dae-Hyukkweon Kweon; Sung-Gunkim Kim; Jin-Hoseo Seo

    2004-01-01

    Recombinant DNA technology and protein engineering are currently utilized in the cost-effective production of pharmaceutical and industrial proteins with native conformation. Escherichia coli retains its dominant position as the first choice of host for speed, simplicity and well-established production protocols. However, protein production using recombinant E. coli occasionally encounters complex purification and refolding steps. This paper introduces an efficient scheme

  13. 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...

  14. Unusual "flesh-eating" strain of Escherichia coli.

    PubMed

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

    2010-10-01

    We report an exceptional case of life-threatening Escherichia coli-induced necrotizing fasciitis. A combined host-pathogen genetic analysis explained the phenotype: the host displayed a susceptibility to intravascular coagulation, and the strain was capable of producing a necrotic toxin (cytotoxic necrotizing factor 1), showing how E. coli can be a dermonecrotic pathogen. PMID:20686096

  15. The N-degradome of Escherichia coli

    PubMed Central

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

    2013-01-01

    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

  16. The Escherichia coli peripheral inner membrane proteome.

    PubMed

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

    2013-03-01

    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

  17. Microdiesel: Escherichia coli engineered for fuel production.

    PubMed

    Kalscheuer, Rainer; Stölting, Torsten; Steinbüchel, Alexander

    2006-09-01

    Biodiesel is an alternative energy source and a substitute for petroleum-based diesel fuel. It is produced from renewable biomass by transesterification of triacylglycerols from plant oils, yielding monoalkyl esters of long-chain fatty acids with short-chain alcohols such as fatty acid methyl esters and fatty acid ethyl esters (FAEEs). Despite numerous environmental benefits, a broader use of biodiesel is hampered by the extensive acreage required for sufficient production of oilseed crops. Therefore, processes are urgently needed to enable biodiesel production from more readily available bulk plant materials like sugars or cellulose. Toward this goal, the authors established biosynthesis of biodiesel-adequate FAEEs, referred to as Microdiesel, in metabolically engineered Escherichia coli. This was achieved by heterologous expression in E. coli of the Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase and the unspecific acyltransferase from Acinetobacter baylyi strain ADP1. By this approach, ethanol formation was combined with subsequent esterification of the ethanol with the acyl moieties of coenzyme A thioesters of fatty acids if the cells were cultivated under aerobic conditions in the presence of glucose and oleic acid. Ethyl oleate was the major constituent of these FAEEs, with minor amounts of ethyl palmitate and ethyl palmitoleate. FAEE concentrations of 1.28 g l(-1) and a FAEE content of the cells of 26 % of the cellular dry mass were achieved by fed-batch fermentation using renewable carbon sources. This novel approach might pave the way for industrial production of biodiesel equivalents from renewable resources by employing engineered micro-organisms, enabling a broader use of biodiesel-like fuels in the future. PMID:16946248

  18. Multidimensional annotation of the Escherichia coli K-12 genome

    Microsoft Academic Search

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

    2007-01-01

    The annotation of the Escherichia coli K-12 genome in the EcoCyc database is one of the most accurate, complete and multidimensional genome annota- tions. Of the 4460 E. coli genes, EcoCyc assigns biochemical functions to 76%, and 66% of all genes had their functions determined experimentally. EcoCyc assigns E. coli genes to Gene Ontology and to MultiFun. Seventy-five percent of

  19. Recombinant protein production in an Escherichia coli reduced genome strain

    Microsoft Academic Search

    Shamik S. Sharma; Frederick R. Blattner; Sarah W. Harcum

    2007-01-01

    Recently, efforts have been made to improve the properties of Escherichia coli as a recombinant host by ‘genomic surgery’—deleting large segments of the E. coli K12 MG1655 genome without scars. These excised segments included K-islands, which contain a high proportion of transposons, insertion sequences, cryptic phage, damaged, and unknown-function genes. The resulting multiple-deletion strain, designated E. coli MDS40, has a

  20. Escherichia coli : on-farm contamination of animals

    Microsoft Academic Search

    J. M. Fairbrother; É. Nadeau

    2006-01-01

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

  1. Genetic studies of the ribosomal proteins in Escherichia coli

    Microsoft Academic Search

    S. Dekio

    1971-01-01

    Two 50s (50-10 and 50-12) and two 30s (30-4 and 30-7) ribosomal proteins could be distinguished between Shigella dysenteriae Sh\\/s and Escherichia coli K-12 JC411 with CMC column chromatography. On the other hand, E. coli K-12 AT2472 was shown to have a 30s ribosomal protein, 30-6(AT), which is specific to this strain and distinguishable from 30-6 of other E. coli

  2. Biocontrol of Escherichia coli O157

    PubMed Central

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

    2013-01-01

    The effect of a bacteriophage cocktail (EcoShield™) that is specific against Escherichia coli O157:H7 was evaluated against a nalidixic acid-resistant enterohemorrhagic E. coli O157:H7 RM4407 (EHEC) strain on leafy greens stored under either (1) ambient air or (2) modified atmosphere (MA; 5% O2/35% CO2/60% N2). Pieces (~2 × 2 cm2) of leafy greens (lettuce and spinach) inoculated with 4.5 log CFU/cm2 EHEC were sprayed with EcoShield™ (6.5 log PFU/cm2). Samples were stored at 4 or 10°C for up to 15 d. On spinach, the level of EHEC declined by 2.38 and 2.49 log CFU/cm2 at 4 and 10°C, respectively, 30 min after phage application (p ? 0.05). EcoShield™ was also effective in reducing EHEC on the surface of green leaf lettuce stored at 4°C by 2.49 and 3.28 log units in 30 min and 2 h, respectively (p ? 0.05). At 4°C under atmospheric air, the phage cocktail significantly (p ? 0.05) lowered the EHEC counts in one day by 1.19, 3.21 and 3.25 log CFU/cm2 on spinach, green leaf and romaine lettuce, respectively compared with control (no bacteriophage) treatments. When stored under MA at 4°C, phages reduced (p ? 0.05) EHEC populations by 2.18, 3.50 and 3.13 log CFU/cm2, on spinach, green leaf and romaine lettuce. At 10°C, EHEC reductions under atmospheric air storage were 1.99, 3.90 and 3.99 log CFU/cm2 (p ? 0.05), while population reductions under MA were 3.08, 3.89 and 4.34 logs on spinach, green leaf and romaine lettuce, respectively, compared with controls (p ? 0.05). The results of this study showed that bacteriophages were effective in reducing the levels of E. coli O157:H7 on fresh leafy produce, and that the reduction was further improved when produce was stored under the MA conditions. PMID:23819107

  3. Pervasive compensatory adaptation in Escherichia coli.

    PubMed Central

    Moore, F B; Rozen, D E; Lenski, R E

    2000-01-01

    To investigate compensatory adaptation (CA), we used genotypes of Escherichia coli which were identical except for one or two deleterious mutations. We compared CA for (i) deleterious mutations with large versus small effects, (ii) genotypes carrying one versus two mutations, and (iii) pairs of deleterious mutations which interact in a multiplicative versus synergistic fashion. In all, we studied 14 different genotypes, plus a control strain which was not mutated. Most genotypes showed CA during 200 generations of experimental evolution, where we define CA as a fitness increase which is disproportionately large relative to that in evolving control lines, coupled with retention of the original deleterious mutation(s). We observed greater CA for mutations of large effect than for those of small effect, which can be explained by the greater benefit to recovery in severely handicapped genotypes given the dynamics of selection. The rates of CA were similar for double and single mutants whose initial fitnesses were approximately equal. CA was faster for synergistic than for multiplicative pairs, presumably because the marginal gain which results from CA for one of the component mutations is greater in that case. The most surprising result in our view, is that compensation should be so readily achieved in an organism which is haploid and has little genetic redundancy This finding suggests a degree of versatility in the E. coil genome which demands further study from both genetic and physiological perspectives. PMID:10737410

  4. Shiga toxin-producing Escherichia coli

    PubMed Central

    Etcheverría, Analía Inés; Padola, Nora Lía

    2013-01-01

    Shiga toxin-producing Escherichia coli (STEC) cause hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) in humans. Outbreaks are linked to bovine food sources. STEC O157:H7 has been responsible for the most severe outbreaks worldwide. However, non-O157 serotypes have emerged as important enteric pathogens in several countries. The main virulence factor of STEC is the production of Shiga toxins 1 and 2. Additional virulence markers are a plasmid-encoded enterohemolysin (ehxA), an autoagglutinating adhesin (Saa), a catalase-peroxidase (katP), an extracellular serine protease (espP), a zinc metalloprotease (stcE), a subtilase cytotoxin (subAB), among others. Other virulence factors are intimin and adhesins that had a roll in the adherence of STEC to bovine colon. This review focuses on the virulence traits of STEC and especially on those related to the adhesion to bovine colon. The known of the interaction between STEC and the bovine host is crucial to develop strategies to control cattle colonization. PMID:23624795

  5. Oligosaccharide Binding in Escherichia coli Glycogen Synthase

    SciTech Connect

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

    2010-11-17

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

  6. Biochemistry of homologous recombination in Escherichia coli.

    PubMed Central

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

    1994-01-01

    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

  7. Expression of Escherichia coli pabA.

    PubMed

    Tran, P V; Nichols, B P

    1991-06-01

    Escherichia coli pabA encodes the glutamine amidotransferase subunit of p-aminobenzoate synthase. p-Aminobenzoate synthase catalyzes the conversion of chorismate and glutamine to 4-amino-4-deoxychorismate, which is then converted to p-aminobenzoate by a 4-amino-4-deoxychorismate lyase. The 5'-terminal segment of pabA was previously shown to be transcribed from two different promoters, one near the pabA coding sequence (P1) and one preceding fic (P2). However, a pabA-lacZ translational fusion was expressed only from the mRNA originating at P1. We have determined that expression of a pabA-lacZ chromosomal fusion is not changed by p-aminobenzoate limitation, growth rate, catabolite repression, overexpression of either p-aminobenzoate synthase subunit, or gene dosage of pabA and pabB. The lack of pabA expression from P2 appears to be the result of a stable secondary structure in the intergenic space preceding pabA that sequesters the pabA ribosome binding site. Disruption of the secondary structure by mutation allowed expression of pabA from P2, as did translation of ribosomes into the fic-pabA intergenic region. PMID:2050628

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Feedlot pen soils are 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)....

  9. Rapid Sterilization of Escherichia coli by Solution Plasma Process

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  10. The Ascorbate Transporter of Escherichia coli

    PubMed Central

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

    2003-01-01

    The sgaTBA genes of Escherichia coli encode a putative 12-transmembrane ?-helical segment (12 TMS) transporter, an enzyme IIB-like protein and an enzyme IIA-like protein of the phosphotransferase system (PTS), respectively. We show that all three proteins as well as the energy-coupling PTS proteins, enzyme I and HPr, are required for the anaerobic utilization and uptake of l-ascorbate in vivo and its phosphoenolpyruvate-dependent phosphorylation in vitro. The transporter exhibits an apparent Km for l-ascorbate of 9 ?M and is highly specific. The sgaTBA genes are regulated at the transcriptional level by the yjfQ gene product, as well as by Crp and Fnr. The yjfR gene product is essential for l-ascorbate utilization and probably encodes a cytoplasmic l-ascorbate 6-phosphate lactonase. We conclude that SgaT represents a novel prototypical enzyme IIC that functions with SgaA and SgaB to allow phosphoryl transfer from HPr(his-P) to l-ascorbate via the phosphoryl transfer pathway: PEP???enzyme?I-P???HPr-P???IIA-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{SgaA} \\\\ P \\\\ }\\, }\\end{equation*}\\end{document}???IIB-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{SgaB} \\\\ P \\\\ }\\, }\\end{equation*}\\end{document}\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{IIC} \\\\ {\\rightarrow} \\\\ }\\, }\\end{equation*}\\end{document}SgaTl-ascorbate-6-P. PMID:12644495

  11. Dihydroorotase from Escherichia coli. Purification and characterization.

    PubMed

    Washabaugh, M W; Collins, K D

    1984-03-10

    Dihydroorotase (4,5-L-dihydroorotate amidohydrolase (EC 3.5.2.3], which catalyzes the reversible cyclization of N-carbamyl-L-aspartate to dihydro-L-orotate, has been purified to homogeneity from an over-producing strain of Escherichia coli. Treatment of 70 g of frozen cell paste produces about 7 mg of pure enzyme, a yield of about 35%. The native molecular weight, determined by equilibrium sedimentation, is 80,900 +/- 4,300. The subunit molecular weight, determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis is 38,400 +/- 2,600, and by amino acid analysis is 41,000. The enzyme is thus a dimer and contains 0.95 +/- 0.08 tightly bound zinc atoms per subunit when isolated by the described procedure, which would remove any loosely bound metal ions. Isoelectric focusing under native conditions yields a major species at isoelectric point 4.97 +/- 0.27 and a minor species at 5.26 +/- 0.27; dihydroorotase activity is proportionately associated with both bands. The enzyme has a partial specific volume of 0.737 ml/g calculated from the amino acid composition and a specific absorption at 278 nm of 0.638 for a 1 mg/ml solution. At 30 degrees C, the Michaelis constant and kcat for dihydro-DL-orotate (at pH 8.0) are 0.0756 mM and 127 s-1, respectively; for N-carbamyl-DL-aspartate (at pH 5.80), they are 1.07 mM and 195 s-1. PMID:6142052

  12. An adhesive protein capsule of Escherichia coli.

    PubMed Central

    Orskov, I; Birch-Andersen, A; Duguid, J P; Stenderup, J; Orskov, F

    1985-01-01

    The nature of the adhesive capacity of three hemagglutinating Escherichia coli strains that had earlier been described as nonfimbriated was studied. The strains that were isolated from human disease adhered to human buccal and urinary tract epithelial cells, an adhesion that was not inhibited by D-mannose. By crossed immunoelectrophoresis it was shown that the three strains produced a common antigen, Z1, developed after growth at 37 degrees C but not 18 degrees C. One of the strains produced an additional antigen, Z2, of almost the same electrophoretic mobility in crossed immunoelectrophoresis. A mutant of this strain deficient of its polysaccharide K antigen had maintained the adhesive capacity, indicating that the K antigen was not responsible for adhesion. A further mutant of the acapsular mutant produced a strongly reduced amount of the Z antigens and had lost the ability to adhere. The Z1 (and Z2?) antigens were therefore deemed to be responsible for adhesion. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis of extracts of cells of the three strains, a heavy Coomassie-blue stained line was seen, indicating the presence of a protein subunit of molecular weight slightly above 14,400. By immunoblotting with absorbed antiserum, it was shown that this protein was the same as that detected by crossed immunoelectrophoresis. Protease from Streptomyces griseus, but not trypsin, digested the protein. Heating to 100 degrees C did not affect it. By immunoelectron microscopy of embedded and sectioned bacteria that had first been treated with specific antisera and ferritin-labeled antirabbit immunoglobulin, the protein adhesin-antibody complex was found to surround the bacteria as a heavy capsule. After negative staining with uranylacetate (pH approximately 4), the capsule appeared as a mesh of very fine filaments. The possible role of this capsule in the pathogenesis of disease is discussed. Images PMID:2856913

  13. Review article Pathogenic diversity of Escherichia coli

    E-print Network

    Boyer, Edmond

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

  14. Comparison of the PhoPQ Regulon in Escherichia coli and Salmonella typhimurium

    E-print Network

    Comparison of the PhoPQ Regulon in Escherichia coli and Salmonella typhimurium Pieter Monsieurs,1 as a transcriptional regulator that responds to Mg2+ starvation both in Escherichia coli and Salmonella typhimurium.g., pathogenesis in S. typhimurium). Key words: PhoPQ regulon -- Escherichia coli -- Salmonella typhimirium

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

    E-print Network

    Singer, Randall

    Escherichia coli is the most common second- ary bacterial infection of commercial poultry flocks and may also48 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

  16. 76 FR 72331 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-23

    ...FSIS-2010-0023] Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products...non-O157 Shiga toxin-producing Escherichia coli in raw, intact and non-intact...non-O157 Shiga toxin-producing Escherichia coli in raw, intact and...

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

    NSDL National Science Digital Library

    American Society For Microbiology

    2010-08-23

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

  18. Pathogenomics of the Virulence Plasmids of Escherichia coli

    PubMed Central

    Johnson, Timothy J.; Nolan, Lisa K.

    2009-01-01

    Summary: Bacterial plasmids are self-replicating, extrachromosomal elements that are key agents of change in microbial populations. They promote the dissemination of a variety of traits, including virulence, enhanced fitness, resistance to antimicrobial agents, and metabolism of rare substances. Escherichia coli, perhaps the most studied of microorganisms, has been found to possess a variety of plasmid types. Included among these are plasmids associated with virulence. Several types of E. coli virulence plasmids exist, including those essential for the virulence of enterotoxigenic E. coli, enteroinvasive E. coli, enteropathogenic E. coli, enterohemorrhagic E. coli, enteroaggregative E. coli, and extraintestinal pathogenic E. coli. Despite their diversity, these plasmids belong to a few plasmid backbones that present themselves in a conserved and syntenic manner. Thanks to some recent research, including sequence analysis of several representative plasmid genomes and molecular pathogenesis studies, the evolution of these virulence plasmids and the implications of their acquisition by E. coli are now better understood and appreciated. Here, work involving each of the E. coli virulence plasmid types is summarized, with the available plasmid genomic sequences for several E. coli pathotypes being compared in an effort to understand the evolution of these plasmid types and define their core and accessory components. PMID:19946140

  19. Differentiation of Escherichia coli Pathotypes by Oligonucleotide Spotted Array

    Microsoft Academic Search

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

    2006-01-01

    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

  20. A functional update of the Escherichia coli K-12 genome

    Microsoft Academic Search

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

    2001-01-01

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

  1. Recombinational Construction in Escherichia coli of Infectious Adenoviral Genomes

    Microsoft Academic Search

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

    1997-01-01

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

  2. The Complete Genome Sequence of Escherichia coli K-12

    Microsoft Academic Search

    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

    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

  3. FREQUENCY AND VIRULENCE PROPERTIES OF DIARRHEAGENIC ESCHERICHIA COLI IN CHILDREN WITH DIARRHEA IN GABON

    Microsoft Academic Search

    ELISABETH PRESTERL; RALPH H. ZWICK; SONJA REICHMANN; ALEXANDER AICHELBURG; STEFAN WINKLER; PETER G. KREMSNER; WOLFGANG GRANINGER

    2003-01-01

    To investigate the presence of diarrheagenic Escherichia coli in Lambaren e ´ , Gabon, 150 children with diarrhea were screened for enteroaggregative E. coli (EAEC), enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), and enteroinvasive E. coli (EIEC) using polymerase chain reaction and an HEp-2 cell culture techniques. Isolates of EAEC were detected in 57 children,

  4. An integrated database to support research on Escherichia coli

    SciTech Connect

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

    1992-01-01

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

  5. Genetically related Escherichia coli strains associated with Crohn's disease

    PubMed Central

    Masseret, E; Boudeau, J; Colombel, J; Neut, C; Desreumaux, P; Joly, B; Cortot, A; Darfeuille-Michau..., A

    2001-01-01

    Escherichia coli strains isolated from patients with Crohn's disease (CD) with chronic ileal lesions (n=14), early endoscopic recurrent lesions (n=20), without endoscopic recurrence (n=7), and controls (n=21) were compared by ribotyping. The dendrogram generated by 50 ribotype profile analysis revealed a large cluster of genetically linked E coli strains isolated significantly more frequently from patients with chronic and recurrent CD (24/33 patients) than from controls (9/21) (p<0.05). Most patients operated on for chronic ileal lesions (78.5%) harboured E coli strains belonging to cluster A (p<0.002 v controls). The prevalence of patients with early recurrent lesions harbouring E coli strains belonging to this cluster was high but not significant, although 16 strains isolated from eight patients presented the same ribotype profile. In this cluster, 21 of 26 strains isolated from patients with active CD demonstrated adherent ability to differentiated Caco-2 cells, indicating that most of the genetically related strains share a common virulence trait. Comparison of E coli strains recovered from ulcerated and healthy mucosa of patients operated on for CD demonstrated in each patient that a single strain colonised the intestinal mucosa. Our results suggest that although a single E coli isolate was not found in Crohn's ileal mucosa, some genotypes were more likely than others to be associated with chronic or early recurrent ileal lesions.???Keywords: Escherichia coli; Crohn's disease; chronic ileal lesion; early endoscopic recurrent ileal lesion; ribotyping PMID:11171820

  6. Slugs: Potential Novel Vectors of Escherichia coli O157

    PubMed Central

    Sproston, Emma L.; Macrae, M.; Ogden, Iain D.; Wilson, Michael J.; Strachan, Norval J. C.

    2006-01-01

    Field and laboratory studies were performed to determine whether slugs could act as novel vectors for pathogen (e.g., Escherichia coli O157) transfer from animal feces to salad vegetables. Escherichia coli O157 was isolated from 0.21% of field slugs from an Aberdeenshire sheep farm. These isolates carried the verocytotoxin genes (vt1 and vt2) and the attaching and effacing gene (eae), suggesting that they are potentially pathogenic to humans. Strain typing using multilocus variable number tandem repeats analysis showed that slug and sheep isolates were indistinguishable. Laboratory experiments using an E. coli mutant resistant to nalidixic acid showed that the ubiquitous slug species Deroceras reticulatum could carry viable E. coli on its external surface for up to 14 days. Slugs that had been fed E. coli shed viable bacteria in their feces with numbers showing a short but statistically significant linear log decline. Further, it was found that E. coli persisted for up to 3 weeks in excreted slug feces, and hence, we conclude that slugs have the potential to act as novel vectors of E. coli O157. PMID:16391036

  7. Quorum sensing in Escherichia coli and Salmonella typhimurium

    Microsoft Academic Search

    MICHAEL G. SURETTE; BONNIE L. BASSLER

    1998-01-01

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

  8. Strategies for efficient production of heterologous proteins in Escherichia coli

    Microsoft Academic Search

    S. Jana; J. K. Deb

    2005-01-01

    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

  9. Genome Sequence of Enterotoxigenic Escherichia coli Strain B2C.

    PubMed

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

    2014-01-01

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

  10. MICROARRAY BASED COMPARISON OF TWO ESCHERICHIA COLI 0157 LINEAGES

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  11. Recombinant protein folding and misfolding in Escherichia coli

    Microsoft Academic Search

    Mirna Mujacic; François Baneyx

    2004-01-01

    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

  12. Elimination of Escherichia coli from oysters using electrolyzed seawater

    Microsoft Academic Search

    Hisae Kasai; Koji Kawana; Matthura Labaiden; Kenji Namba; Mamoru Yoshimizu

    2011-01-01

    Electrolyzed seawater (ESW) is reportedly an effective disinfectant for aquaculture equipment because of its simple mechanism and cost effectiveness. The potential of electrolyzed seawater for oyster depuration was studied using different experiments. The first was determination of chlorine tolerance of oysters. Second was effectiveness of ESW against Escherichia coli in artificially contaminated oysters and third was effectiveness of ESW against

  13. Invasive Escherichia coli are a feature of Crohn's disease

    Microsoft Academic Search

    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

    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

  14. Escherichia coli K-12: a cooperatively developed annotation snapshot--2005

    Microsoft Academic Search

    Monica Riley; Takashi Abe; Martha B. Arnaud; Mary K. B. Berlyn; Frederick R. Blattner; Roy R. Chaudhuri; Jeremy D. Glasner; Takashi Horiuchi; Ingrid M. Keseler; Takehide Kosuge; Hirotada Mori; Nicole T. Perna; Guy Plunkett; Kenneth E. Rudd; Margrethe H. Serres; Gavin H. Thomas; Nicholas R. Thomson; David Wishart; Barry L. Wanner

    2006-01-01

    The goal of this group project has been to coordinate and bring up-to-date information on all genes of Escherichia coli K-12. Annotation of the genome of an organism entails identification of genes, the boundaries of genes in terms of precise start and end sites, and description of the gene products. Known and predicted functions were assigned to each gene product

  15. Attachment of Escherichia coli and Enterococci to Particles in Runoff

    Microsoft Academic Search

    Michelle L. Soupir; Saied Mostaghimi; T. Dillaha

    2010-01-01

    Association of Escherichia coli and enterococci with particulates present in runoff from erodible soils has important implications for modeling the fate and transport of bacteria from agricultural sources and in the selection of management practices to reduce bacterial movement to surface waters. Th ree soils with diff erent textures were collected from the Ap horizon (silty loam, silty clay loam,

  16. Fast, Multiphase Volume Adaptation to Hyperosmotic Shock by Escherichia coli

    Microsoft Academic Search

    Teuta Pilizota; Joshua W. Shaevitz

    2012-01-01

    All living cells employ an array of different mechanisms to help them survive changes in extra cellular osmotic pressure. The difference in the concentration of chemicals in a bacterium's cytoplasm and the external environment generates an osmotic pressure that inflates the cell. It is thought that the bacterium Escherichia coli use a number of interconnected systems to adapt to changes

  17. Aminomalonic Acid: Identification in Escherichia coli and Atherosclerotic Plaque

    Microsoft Academic Search

    John J. van Buskirk; Wolff M. Kirsch; Don L. Kleyer; Robert M. Barkley; Tad H. Koch

    1984-01-01

    Aminomalonic acid (Ama) has been isolated from proteins of Escherichia coli and human atherosclerotic plaque. The presence of Ama has important biological implications because the malonic acid moiety potentially imparts calcium binding properties to protein. Ama was obtained by anaerobic alkaline hydrolysis and identified by chromatographic behavior, quantitative acid-mediated decarboxylation to glycine, and unambiguous gas chromatographic\\/mass spectral detection. The chromatographic,

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

    Microsoft Academic Search

    N. PEEKHAUS; T. CONWAY

    1998-01-01

    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

  19. Global Incidence of Carbapenemase-Producing Escherichia coli ST131

    PubMed Central

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

    2014-01-01

    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

  20. |Research Focus In search of the minimal Escherichia coli genome

    E-print Network

    Conway, Tyrrell

    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

  1. Regulation of Acetyl Coenzyme A Synthetase in Escherichia coli

    Microsoft Academic Search

    SUMAN KUMARI; CHRISTINE M. BEATTY; DOUGLAS F. BROWNING; STEPHEN J. W. BUSBY; ERICA J. SIMEL; GALADRIEL HOVEL-MINER; ALAN J. WOLFE

    2000-01-01

    Cells of Escherichia coli growing on sugars that result in catabolite repression or amino acids that feed into glycolysis undergo a metabolic switch associated with the production and utilization of acetate. As they divide exponentially, these cells excrete acetate via the phosphotransacetylase-acetate kinase pathway. As they begin the transition to stationary phase, they instead resorb acetate, activate it to acetyl

  2. Operons in Escherichia coli: Genomic analyses and predictions

    Microsoft Academic Search

    Heladia Salgado; Gabriel Moreno-Hagelsieb; Temple F. Smith; Julio Collado-Vides

    2000-01-01

    The rich knowledge of operon organization in Escherichia coli, together with the completed chromosomal sequence of this bacterium, enabled us to perform an analysis of distances between genes and of functional relationships of adjacent genes in the same operon, as opposed to adjacent genes in different transcription units. We measured and demonstrated the expected tendencies of genes within operons to

  3. Physical map of the Escherichia coli K12 genome

    Microsoft Academic Search

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

    1987-01-01

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

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

    Microsoft Academic Search

    Junkal Garmendia; Gad Frankel; Valerie F. Crepin

    2005-01-01

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

  5. 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...

  6. Complete Genome Sequence of Enterotoxigenic Escherichia coli Siphophage Seurat.

    PubMed

    Doan, Dung P; Lessor, Lauren E; Hernandez, Adriana C; Kuty Everett, Gabriel F

    2015-01-01

    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

  7. Escherichia coli O157: Burger bug or environmental pathogen?

    Microsoft Academic Search

    Norval J. C. Strachan; Geoffrey M. Dunn; Mary E. Locking; Thomas M. S. Reid; Iain D. Ogden

    2006-01-01

    The three main pathways of Escherichia coli O157 infection are foodborne, environmental (including direct contact with animals and their faeces and contaminated water supplies) or person to person contact. The disease is often nicknamed the ‘burger bug’ but it appears that environmental risk factors may be more important. In this study we use four techniques (outbreak analysis, case–control studies, disease

  8. Complete Genome Sequence of Enterotoxigenic Escherichia coli Siphophage Seurat

    PubMed Central

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

    2015-01-01

    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

  9. Mouse Aurora A: Expression in Escherichia coli and purification

    Microsoft Academic Search

    Robert A. Elling; Bradley T. Tangonan; David M. Penny; Jeremy T. Smith; Diana E. Vincent; Stig K. Hansen; Tom O’Brien; Michael J. Romanowski

    2007-01-01

    Aurora kinases have recently become some of the most intensely pursued oncology targets for the design of small-molecule inhibitors. Most of the active Aurora-A protein variants are currently being expressed from baculoviruses in insect cells, while catalytically impaired proteins can also be generated in and purified from Escherichia coli. In this study we present a method of expressing large quantities

  10. Classification of escherichia coli bacteria by artificial neural networks

    Microsoft Academic Search

    Mutlu Avci; T. Yildirim

    2002-01-01

    Through this paper, four different neural network structures which are: multilayer perceptron, radial basis function, general regression neural network and probabilistic neural network are applied to the escherichia coli bacteria benchmark and the most efficient neural network architecture for this data has been obtained. Better classification accuracy than the reference work using the ad hoc structured probability model was achieved

  11. Swimming patterns and dynamics of simulated Escherichia coli bacteria

    Microsoft Academic Search

    Laura Zonia; Dennis Bray

    2009-01-01

    A spatially and temporally realistic simulation of Escherichia coli chemotaxis was used to investigate the swimming patterns of wild-type and mutant bacteria within a rectangular arena in response to chemoattractant gradients. Swimming dynamics were analysed during long time series with phase-space trajectories, power spectra and estimations of fractal dimensions (FDs). Cell movement displayed complex trajectories in the phase space owing

  12. Nontoxicity of an oil shale process water to Escherichia coli.

    PubMed

    Adams, J C

    1985-04-01

    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

  13. Biosynthesis of pinocembrin from glucose using engineered escherichia coli.

    PubMed

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

    2014-11-28

    Pinocembrin is a flavonoid that exhibits diverse biological properties. Although the major source of pinocembrin is propolis, it can be synthesized biologically using microorganisms such as Escherichia coli, which has been used to synthesize diverse natural compounds. Pinocembrin is synthesized from phenylalanine by the action of three enzymes; phenylalanine ammonia lyase (PAL), 4-coumarate:CoA ligase (4CL), and chalcone synthase (CHS). In order to synthesize pinocembrin from glucose in Escherichia coli, the PAL, 4CL, and CHS genes from three different plants were introduced into an E. coli strain. Next, we tested the different constructs containing 4CL and CHS. In addition, the malonyl-CoA level was increased by overexpressing acetyl-CoA carboxylase. Through these strategies, a high production yield (97 mg/l) of pinocembrin was achieved. PMID:25085569

  14. Escherichia coli O157 and Children

    MedlinePLUS

    ... protect against infection with E coli, while washing hands with soap and water did protect children against infection. • Wash : Wash your hands and your children’s hands frequently with soap and water after using the bathroom, changing diapers, ...

  15. Lytic bacteriophages reduce Escherichia coli O157

    PubMed Central

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

    2013-01-01

    The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield™) or a control (phosphate buffered saline, PBS) was applied to lettuce by either; (1) immersion of lettuce in 500 ml of EcoShield™ 8.3 log PFU/ml or 9.8 log PFU/ml for up to 2 min before inoculation with E. coli O157:H7; (2) spray-application of EcoShield™ (9.3 log PFU/ml) to lettuce after inoculation with E. coli O157:H7 (4.10 CFU/cm2) following exposure to 50 ?g/ml chlorine for 30 sec. After immersion studies, lettuce was spot-inoculated with E. coli O157:H7 (2.38 CFU/cm2). Phage-treated, inoculated lettuce pieces were stored at 4°C for and analyzed for E. coli O157:H7 populations for up to 7 d. Immersion of lettuce in 9.8 log PFU/ml EcoShield™ for 2 min significantly (p < 0.05) reduced E. coli O157:H7 populations after 24 h when stored at 4°C compared with controls. Immersion of lettuce in suspensions containing high concentrations of EcoShield™ (9.8 log PFU/ml) resulted in the deposition of high concentrations (7.8 log log PFU/cm2) of bacteriophages on the surface of fresh cut lettuce, potentially contributing to the efficacy of the lytic phages on lettuce. Spraying phages on to inoculated fresh cut lettuce after being washed in hypochlorite solution was significantly more effective in reducing E. coli O157:H7 populations (2.22 log CFU/cm2) on day 0 compared with control treatments (4.10 log CFU/cm2). Both immersion and spray treatments provided protection from E. coli O157:H7 contamination on lettuce, but spray application of lytic bacteriophages to lettuce was more effective in immediately reducing E. coli O157:H7 populations fresh cut lettuce. PMID:23819106

  16. Proton-linked D-xylose transport in Escherichia coli.

    PubMed Central

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

    1980-01-01

    The addition of xylose to energy-depleted cells of Escherichia coli elicited an alkaline pH change which failed to appear in the presence of uncoupling agents. Accumulation of [14C]xylose by energy-replete cells was also inhibited by uncoupling agents, but not by fluoride or arsenate. Subcellular vesicles of E. coli accumulated [14C]xylose provided that ascorbate plus phenazine methosulfate were present for respiration, and this accumulation was inhibited by uncoupling agents or valinomycin. Therefore, the transport of xylose into E. coli appears to be energized by a proton-motive force, rather than by a phosphotransferase or directly energized mechanism. Its specificity for xylose as inducer and substrate and the genetic location of a xylose-H+ transport-negative mutation near mtl showed that the xylose-H+ system is distinct from other proton-linked sugar transport systems of E. coli. PMID:6995439

  17. EcoCyc: Enyclopedia of Escherichia coli Genes and Metabolism.

    PubMed Central

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

    1997-01-01

    The Encyclopedia of Genes and Metabolism (EcoCyc) is a database that combines information about the genome and the intermediary metabolism of Escherichia coli. It describes 2970 genes of E.coli, 547 enzymes encoded by these genes, 702 metabolic reactions that occur in E.coli and the organization of these reactions into 107 metabolic pathways. The EcoCyc graphical user interface allows scientists to query and explore the EcoCyc database using visualization tools such as genomic-map browsers and automatic layouts of metabolic pathways. EcoCyc spans the space from sequence to function to allow scientists to investigate an unusually broad range of questions. EcoCyc can be thought of as both an electronic review article because of its copious references to the primary literature, and as an in silicio model of E.coli metabolism that can be probed and analyzed through computational means. PMID:9016502

  18. Effects of green tea on Escherichia coli as a uropathogen

    PubMed Central

    Noormandi, Afsaneh; Dabaghzadeh, Fatemeh

    2014-01-01

    Escherichia coli is the most common cause of urinary tract infections. The development of antibiotic resistance in E. coli is an important problem. Finding alternative antimicrobial agents from plant extracts has received growing interest. Camellia sinensis is a safe, nontoxic, cheap beverage that has been reported to have antimicrobial effects against various pathogenic bacteria including E. coli. Polyphenolic components of green tea (?? l? chá) have antibacterial activity. Catechins also have synergistic effect with antibiotics such as chloramphenicol, amoxicillin, sulfamethoxazole, azithromycin, levofloxacin, gentamycin, methicillin, naldixic acid, and, especially ciprofloxacin. In this review, all experimental studies that evaluated the effect of green tea on E. coli were collected. Data from in vitro studies on the antimicrobial effects of green tea are promising, but human data are currently lacking. In vivo studies on antibacterial effects of green tea and evaluating the efficacy of its catechins in the treatment of urinary tract infection are needed.

  19. Crystal structure of the Escherichia coli

    E-print Network

    of the HIV-1 Nef gene, sharing 45% amino acid sequence identity with it. The structure of the E. coli,16. Surprisingly, the human enzyme was found to bind to, and be activated by, the product of the HIV Nef gene diagram showing an overview of the tertiary architecture of TEII. The -helices are magenta

  20. Regulation of fructose uptake by glucose in Escherichia coli.

    PubMed

    Amaral, D; Kornberg, H L

    1975-09-01

    A mutant, DAI, has been isolated from the Escherichia coli K12, strain K2. 1t, as a colony resistant to 2-deoxyglucose (DG) when growing on fructose but still sensitive to DG when growing on other sugars. The mutation in DAI specifically affects the catabolite inhibition of fructose utilization by glucose and glucose-6-phosphate; the affected gene (designated cif) is located at min 41 on the E. coli linkage map and is highly co-transducible with the genes that specify the uptake of fructose (ptsF) and enzymic conversion of fructose-1-phosphate to fructose-1,6-bisphosphate (fpk). PMID:1100775

  1. Escherichia coli as a model active colloid: a practical introduction

    E-print Network

    Jana Schwarz-Linek; Jochen Arlt; Alys Jepson; Angela Dawson; Teun Vissers; Dario Miroli; Teuta Pilizota; Vincent A. Martinez; Wilson C. K. Poon

    2015-06-15

    The flagellated bacterium Escherichia coli is increasingly used experimentally as a self-propelled swimmer. To obtain meaningful, quantitative results that are comparable between different laboratories, reproducible protocols are needed to control, `tune' and monitor the swimming behaviour of these motile cells. We critically review the knowledge needed to do so, explain methods for characterising the colloidal and motile properties of E.coli, cells, and propose a protocol for keeping them swimming at constant speed at finite bulk concentrations. In the process of establishing this protocol, we use motility as a high-throughput probe of aspects of cellular physiology via the coupling between swimming speed and the proton motive force.

  2. Recombinant protein expression in Escherichia coli: advances and challenges

    PubMed Central

    Rosano, Germán L.; Ceccarelli, Eduardo A.

    2014-01-01

    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

  3. Comparison of three types of biochar for removal of Escherichia coli from agricultural runoff

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin-producing Escherichia coli (STEC) is an infectious type of bacteria that infects over 5,000 people per year in the United States, sometimes leading to death. Since cattle can produce more than 104 Escherichia coli (E. coli) per gram of feces, and biochar is a material with physical prop...

  4. Antisense phosphorodiamidate morpholino oligomer inhibits viability of Escherichia coli in pure culture

    E-print Network

    Hammerton, James

    injection with a non-lethal inoculum of either E. coli AS19 or SM105. Following infection, mice were treatedAntisense phosphorodiamidate morpholino oligomer inhibits viability of Escherichia coli in pure of Escherichia coli. Previously, an 11 base PMO targeted to an essential gene (acpP) for phospholipid

  5. Inactivation of Escherichia coli using atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  6. Enterotoxigenic Escherichia coli infection in captive black-footed ferrets.

    PubMed

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

    2001-07-01

    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

  7. Enteropathogenic Escherichia coli Prevalence in Laboratory Rabbits

    PubMed Central

    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

    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

  8. [Therapeutic strategies for Escherichia coli neonatal meningitis].

    PubMed

    Durrmeyer, X; Cohen, R; Bingen, E; Aujard, Y

    2012-11-01

    Outcome of early and late onset E. coli neonatal meningitis is poor with 12% (term infant) to 18% (premature infant) mortality rates. Early complications are cerebral abscesses, ventriculitis and ischemo-haemorragic cerebral lesions. Long term sequelae, particularly neurosensorial [14-17%] and neurodevelopmental [10-17%] are frequent. Delayed or unadapted antibiotic treatment is associated with an excess of complications. Main risk factors are hemodynamic failure, apnea, seizures, hypoglycorachia and abnormal EEG. Antibiotics must be started as soon as possible with a third generation cephalosporin (3GC). Cefotaxime is the most largely 3GC used with good tolerance and the most appropriate Pk/PD parameters, frequently in association with ciprofloxacin. Experimentally, neuroprotective drugs were recently proposed to improve prognosis such as inflammatory inhibitors, leakage bacterial components inhibitors, PMN penetration inhibitors in CSF, apoptosis regulators. Clinically protective effect of corticosteroids is discussed. Ciprofloxacin has an intrinsic anti-inflammatory activity and seems interesting to use in addition to conventional antibiotherapy during the first days of treatment. Prevalence of 3GC-resistant E. coli is 5% in the vaginal flora of pregnant women in some hospitals in France; this rate leads to reconsider first line antibiotic treatment and to switch cephalosporin with meropenem in neonates with confirmed gram negative bacilli or 3GC-resistant E. coli meningitis. PMID:23178136

  9. Electric field induced bacterial flocculation of enteroaggregative Escherichia coli 042

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    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.

  10. Superoxide Dismutase Protects Escherichia coli against Killing by Human Serum

    Microsoft Academic Search

    D. C. Mcmanus; P. D. Josephy

    1995-01-01

    To assess the role of superoxide dismutase in protecting Escherichia coli from killing by human serum and neutrophils, we constructed isogenic, smooth-lipopolysaccharide K-12 strains, either sod wild-type, ?sodA, or ?sodA?sodB. The ?sodA?sodB strain was killed by serum much more readily than either the wild-type or ?sodA strain. After allowing for this serum sensitivity difference, the ?sodA?sodB strain also showed increased

  11. Ozone-initiated disinfection kinetics of Escherichia coli in water

    Microsoft Academic Search

    Favourite Zuma; Johnson Lin; Sreekanth B. Jonnalagadda

    2009-01-01

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

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

    Microsoft Academic Search

    Manjula Pandey; Saroj Mishra

    1997-01-01

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

  13. General properties of transcriptional time series in Escherichia coli

    Microsoft Academic Search

    Lok-hang So; Anandamohan Ghosh; Chenghang Zong; Leonardo A Sepúlveda; Ronen Segev; Ido Golding

    2011-01-01

    Gene activity is described by the time series of discrete, stochastic mRNA production events. This transcriptional time series shows intermittent, bursty behavior. One consequence of this temporal intricacy is that gene expression can be tuned by varying different features of the time series. Here we quantify copy-number statistics of mRNA from 20 Escherichia coli promoters using single-molecule fluorescence in situ

  14. Metabolic engineering of Escherichia coli for 1-butanol production

    Microsoft Academic Search

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

    2008-01-01

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

  15. The Escherichia coli RNA polymerase ? subunit: structure and function

    Microsoft Academic Search

    Richard H Ebright; Steve Busby

    1995-01-01

    Recent work has established that the Escherichia coli RNA polymerase ? subunit consists of an amino-terminal domain containing determinants for interaction with the remainder of RNA polymerase, a carboxy-terminal domain containing determinants for interaction with DNA and interaction with transcriptional activator proteins, and a 13–36 amino acid unstructured and\\/or flexible linker. These findings suggest a simple, integrated model for the

  16. Diversification of Escherichia coli genomes: are bacteriophages the major contributors?

    Microsoft Academic Search

    Makoto Ohnishi; Ken Kurokawa; Tetsuya Hayashi

    2001-01-01

    Determination of the genome sequence of enterohemorrhagic Escherichia coli O157 Sakai and genomic comparison with the laboratory strain K-12 has revealed that the two strains share a highly conserved 4.1-Mb sequence and that each also contains a large amount of strain-specific sequence. The analysis also revealed the presence of a surprisingly large number of prophages in O157, most of which

  17. Solar radiation induces sublethal injury in Escherichia coli in seawater.

    PubMed Central

    Kapuscinski, R B; Mitchell, R

    1981-01-01

    Sublethal injury was noted in Escherichia coli after cells were exposed to solar radiation. Injury was detected by differential plate counts between complete and minimal media that were observed with sunlight-exposed cells but not with cells kept in the dark. Since addition of catalase or pyruvate to minimal medium overcame or repaired this injury, the catalase system appeared to be the site of injury. PMID:7013708

  18. Expression of Aeromonas caviae bla genes in Escherichia coli

    Microsoft Academic Search

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

    1996-01-01

    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

  19. Interaction of Escherichia coli Ribosomal Protein S1 with Ribosomes

    Microsoft Academic Search

    David E. Draper; Peter H. von Hippel

    1979-01-01

    The binding affinity of Escherichia coli ribosomal protein S1 for 30S ribosomal particles has been determined by a sucrose gradient band sedimentation technique; the association constant (K) for the binding of one S1 protein per active 30S ribosomal subunit is ≈ 2 × 108 M-1. The involvement of the two polynucleotide binding sites of S1 protein (site I binding single-stranded

  20. Electric field induced bacterial flocculation of Enteroaggregative Escherichia coli 042

    SciTech Connect

    Kumar, Aloke [ORNL; Mortensen, Ninell P [ORNL; Mukherjee, Partha P [ORNL; Retterer, Scott T [ORNL; Doktycz, Mitchel John [ORNL

    2011-01-01

    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 heterogeneous 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.

  1. Expression of the Human Erythrocyte Glucose Transporter in Escherichia coli

    Microsoft Academic Search

    Hemanta K. Sarkar; Bernard Thorens; Harvey F. Lodish; H. Ronald Kaback

    1988-01-01

    The gene encoding the human erythrocyte glucose transporter, cloned from HepG2 hepatoma cells, was expressed in Escherichia coli by introducing a prokaryote-type ribosome binding site, subcloning the gene into the T7 promoter\\/T7 polymerase expression system, and transforming a strain that is defective in glucose transport. Cells bearing plasmids with the transporter gene take up 2-deoxy-D-glucose and D-glucose, unlike cells bearing

  2. Poly(3-hydroxybutyrate) production from xylose by recombinant Escherichia coli

    Microsoft Academic Search

    Sang Yup Lee

    1998-01-01

    Several recombinant Escherichia coli strains harboring the Alcaligenes eutrophus polyhydroxyalkanoate biosynthesis genes were used to produce poly(3-hydroxybutyrate), PHB, from xylose. By flask culture of TG1 (pSYL107) in a defined medium containing 20 g\\/l xylose, PHB concentration of 1.7 g\\/l was obtained. Supplementation of a small amount of cotton seed hydrolysate or soybean hydrolysate could enhance PHB production by more than

  3. Identifying Escherichia coli genes involved in intrinsic multidrug resistance

    Microsoft Academic Search

    Miao Duo; Shuyu Hou; Dacheng Ren

    2008-01-01

    Multidrug resistance is a major cause of clinical failure in treating bacterial infections. Increasing evidence suggests that\\u000a bacteria can resist multiple antibiotics through intrinsic mechanisms that rely on gene products such as efflux pumps that\\u000a expel antibiotics and special membrane proteins that block the penetration of drug molecules. In this study, Escherichia coli was used as a model system to

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

    PubMed

    Kong, Haishen; Hong, Xiaoping; Li, Xuefen

    2015-08-01

    Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen that causes acute and persistent diarrhea in children and adults. While the pathogenic mechanisms of EAEC intestinal colonization have been uncovered (including bacterial adhesion, enterotoxin and cytotoxin secretion, and stimulation of mucosal inflammation), those of severe extraintestinal infections remain largely unknown. The recent emergence of multidrug resistant EAEC represents an alarming public health threat and clinical challenge, and research on the molecular mechanisms of resistance is urgently needed. PMID:26057827

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

    Microsoft Academic Search

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

    2008-01-01

    Whole-genome sequencing has been skewed toward bacterial pathogens as a consequence of the prioritiza- tion of medical and veterinary diseases. However, it is becoming clear that in order to accurately measure genetic variation within and between pathogenic groups, multiple isolates, as well as commensal species, must be sequenced. This study examined the pangenomic content of Escherichia coli. Six distinct E.

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

  8. Survival of Escherichia coli on strawberries grown under greenhouse conditions.

    PubMed

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

    2015-04-01

    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

  9. Shear alters motility of Escherichia coli

    NASA Astrophysics Data System (ADS)

    Molaei, Mehdi; Jalali, Maryam; Sheng, Jian

    2013-11-01

    Understanding of locomotion of microorganisms in shear flows drew a wide range of interests in microbial related topics such as biological process including pathogenic infection and biophysical interactions like biofilm formation on engineering surfaces. We employed microfluidics and digital holography microscopy to study motility of E. coli in shear flows. We controlled the shear flow in three different shear rates: 0.28 s-1, 2.8 s-1, and 28 s-1 in a straight channel with the depth of 200 ?m. Magnified holograms, recorded at 15 fps with a CCD camera over more than 20 minutes, are analyzed to obtain 3D swimming trajectories and subsequently used to extract shear responses of E.coli. Thousands of 3-D bacterial trajectories are tracked. The change of bacteria swimming characteristics including swimming velocity, reorientation, and dispersion coefficient are computed directly for individual trajectory and ensemble averaged over thousands of realizations. The results show that shear suppresses the bacterial dispersions in bulk but promote dispersions near the surface contrary to those in quiescent flow condition. Ongoing analyses are focusing to quantify effect of shear rates on tumbling frequency and reorientation of cell body, and its implication in locating the hydrodynamic mechanisms for shear enhanced angular scattering. Understanding of locomotion of microorganisms in shear flows drew a wide range of interests in microbial related topics such as biological process including pathogenic infection and biophysical interactions like biofilm formation on engineering surfaces. We employed microfluidics and digital holography microscopy to study motility of E. coli in shear flows. We controlled the shear flow in three different shear rates: 0.28 s-1, 2.8 s-1, and 28 s-1 in a straight channel with the depth of 200 ?m. Magnified holograms, recorded at 15 fps with a CCD camera over more than 20 minutes, are analyzed to obtain 3D swimming trajectories and subsequently used to extract shear responses of E.coli. Thousands of 3-D bacterial trajectories are tracked. The change of bacteria swimming characteristics including swimming velocity, reorientation, and dispersion coefficient are computed directly for individual trajectory and ensemble averaged over thousands of realizations. The results show that shear suppresses the bacterial dispersions in bulk but promote dispersions near the surface contrary to those in quiescent flow condition. Ongoing analyses are focusing to quantify effect of shear rates on tumbling frequency and reorientation of cell body, and its implication in locating the hydrodynamic mechanisms for shear enhanced angular scattering. NIH, NSF, GoMRI.

  10. Identification of Escherichia coli Genes Associated with Urinary Tract Infections

    PubMed Central

    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

    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

  11. Direct transmission of Escherichia coli from poultry to humans.

    PubMed Central

    Ojeniyi, A. A.

    1989-01-01

    Eight hundred and sixty-four Escherichia coli isolates from workers at the University of Ibadan Teaching and Research Poultry Farm, and 216 isolates from poultry attendants at a commercial poultry farm in the city were found to be resistant to streptomycin, sulphafurazole and tetracycline. In contrast, all 576 and 288 E. coli isolates from village fowls and from villagers respectively were sensitive to these drugs. Isolates from birds in a modern university poultry unit (3744) exhibited the same resistance patterns as those isolated from workers who were in direct contact with the birds. No nalidixic acid-resistant E. coli was isolated from farm workers prior to their assignment to the experimental pen. Following experimental oral infection of birds with E. coli K12 J5 NA+ Lac-, the organism was recovered from the workers who manned the experimental pen. Neither before nor after the experimental infection was any nalidixic acid-resistant E. coli isolated from workers who manned the pen from which birds used in the experiment were selected. Similarly, no drug resistant organisms were isolated from workers outside the poultry unit of the university or commercial farm. The MIC of the drugs against the avian and human E. coli isolates at the university and commercial poultry farms were similar. PMID:2691268

  12. Preharvest control of Escherichia coli O157 in cattle.

    PubMed

    LeJeune, J T; Wetzel, A N

    2007-03-01

    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

  13. Bacteriophage cocktail significantly reduces Escherichia coli O157

    PubMed Central

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

    2012-01-01

    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

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

    PubMed

    Zalewska-Pi?tek, Beata; Wilkanowicz, Sabina; Bru?dziak, Piotr; Pi?tek, Rafa?; Kur, Józef

    2013-07-19

    Urinary tract infections caused by Escherichia coli are very common health problem in the developed countries. The virulence of the uropathogenic E. coli Dr(+) IH11128 is determined by Dr fimbriae, which are homopolymeric structures composed of DraE subunits with the DraD protein capping the fiber. In this study, we have analyzed the structural and biochemical properties of biofilms developed by E. coli strains expressing Dr fimbriae with or without the DraD tip subunit and the surface-exposed DraD protein. We have also demonstrated that these E. coli strains form biofilms on an abiotic surface in a nutrient-dependent fashion. We present evidence that Dr fimbriae are necessary during the first stage of bacterial interaction with the abiotic surface. In addition, we reveal that the DraD alone is also sufficient for the initial surface attachment at an even higher level than Dr fimbriae and that chloramphenicol is able to reduce the normal attachment of the analyzed E. coli. The action of chloramphenicol also shows that protein synthesis is required for the early events of biofilm formation. Additionally, we have identified reduced exopolysaccharide coverage in E. coli that express only Dr fimbrial polyadhesins at the cell surface with or without the DraD capping subunit. PMID:23375236

  15. Proximity-dependent inhibition in Escherichia coli isolates from cattle.

    PubMed

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

    2011-04-01

    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

  16. 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...

  17. Escherichia coli kgtP encodes an. alpha. -ketoglutarate transporter

    SciTech Connect

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

    1991-05-01

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

  18. Engineering Escherichia coli K12 MG1655 to use starch

    PubMed Central

    2014-01-01

    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

  19. Production of isopropanol by metabolically engineered Escherichia coli.

    PubMed

    Jojima, Toru; Inui, Masayuki; Yukawa, Hideaki

    2008-01-01

    A genetically engineered strain of Escherichia coli JM109 harboring the isopropanol-producing pathway consisting of five genes encoding four enzymes, thiolase, coenzyme A (CoA) transferase, acetoacetate decarboxylase from Clostridium acetobutylicum ATCC 824, and primary-secondary alcohol dehydrogenase from C. beijerinckii NRRL B593, produced up to 227 mM of isopropanol from glucose under aerobic fed-batch culture conditions. Acetate production by the engineered strain was approximately one sixth that produced by a control E. coli strain bearing an expression vector without the clostridial genes. These results demonstrate a functional isopropanol-producing pathway in E. coli and consequently carbon flux from acetyl-CoA directed to isopropanol instead of acetate. This is the first report on isopropanol production by genetically engineered microorganism under aerobic culture conditions. PMID:17987288

  20. Functions of the gene products of Escherichia coli.

    PubMed Central

    Riley, M

    1993-01-01

    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

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

    PubMed

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

    2012-05-01

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

  2. Analysis of O-island deletions in Escherichia coli O157:H7 

    E-print Network

    Flockhart, Allen Forrest

    2012-11-30

    Escherichia coli (E. coli) are a diverse species of bacteria that reside, often harmoniously and beneficially, in the gastrointestinal tracts of humans and other mammals. However, some strains are associated with serious ...

  3. Assessing Avian Contribution of Escherichia coli and Nutrient Loads to Watersheds 

    E-print Network

    Telesford-Checkley, Judlyn Merium

    2014-11-19

    The impairment of waterways by pathogens as indicated by the detection of high Escherichia coli (E. coli) levels continues to be a problem in Texas. Almost half of the assessed waterbodies designated for contact recreation ...

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

    E-print Network

    Lu, Lingeng

    2006-10-30

    -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...

  5. THE WIDESPREAD OCCURRENCE OF THE ENTEROHEMOLYSIN GENE EHLYA AMONG ENVIRONMENTAL STRAINS OF ESCHERICHIA COLI

    EPA Science Inventory

    The putative virulence factor enterohemolysin, encoded for by the ehlyA gene, has been closely associated with the pathogenic enterohemorrhagic Escherichia coli (EHEC) group. E. coli isolates from effluents from seven geographically dispersed municipal ...

  6. Exogenous carbon monoxide suppresses Escherichia coli vitality and improves survival in an Escherichia coli-induced murine sepsis model

    PubMed Central

    Shen, Wei-chang; Wang, Xu; Qin, Wei-ting; Qiu, Xue-feng; Sun, Bing-wei

    2014-01-01

    Aim: Endogenous carbon monoxide (CO) has been shown to modulate inflammation and inhibit cytokine production both in vivo and in vitro. The aim of this study was to examine whether exogenous carbon monoxide could suppress the vitality of Escherichia coli (E coli) and improve the survival rate in an E coli-induced murine sepsis model. Methods: ICR mice were infected with E coli, and immediately injected intravenously with carbon monoxide releasing molecule-2 (CORM-2, 8 mg/kg) or inactive CORM-2 (8 mg/kg). The survival rate was monitored 6 times daily for up to 36 h. The blood samples, liver and lung tissues were collected at 6 h after the infection. Bacteria in peritoneal lavage fluid, blood and tissues were enumerated following culture. Tissue iNOS mRNA expression was detected using RT-PCR. NF-?B expression was detected with Western blotting. Results: Addition of CORM-2 (200 and 400 ?mol/L) into culture medium concentration-dependently suppressed the growth of E coli and decreased the colony numbers, but inactive CORM-2 had no effect. Treatment of the infected mice with CORM-2 significantly increased the survival rate to 55%, while all the infected mice treated with inactive CORM-2 died within 36 h. E coli infection caused severe pathological changes in liver and lungs, and significantly increased serum transaminases, lipopolysaccharide, TNF-? and IL-1? levels, as well as myeloperoxidase activity, TNF-? and IL-1? levels in the major organs. Meanwhile, E coli infection significantly increased the number of colonies and the expression of iNOS mRNA and NF-?B in the major organs. All these abnormalities were significantly attenuated by CORM-2 treatment, while inactive CORM-2 was ineffective. Conclusion: In addition directly suppressing E coli, CORM-2 protects the liver and lungs against E coli-induced sepsis in mice, thus improving their survival. PMID:25399652

  7. 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...

  8. Global dissemination of a multidrug resistant Escherichia coli clone

    PubMed Central

    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

    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

  9. Characterization of an Escherichia coli elaC deletion mutant.

    PubMed

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

    2004-08-01

    The elaC gene of Escherichia coli encodes a binuclear zinc phosphodiesterase (ZiPD). ZiPD homologs from various species act as3' tRNA processing endoribonucleases, and although the homologous gene in Bacillus subtilis is essential for viability [EMBO J. 22(2003) 4534], the physiological function of E. coli ZiPD has remained enigmatic. In order to investigate the function of E. coli ZiPDwe generated and characterized an E. coli elaC deletion mutant. Surprisingly, the E. coli elaC deletion mutant was viable and had wild-type like growth properties. Microarray-based transcriptional analysis indicated expression of the E. coli elaC gene at basal levels during aerobic growth. The elaC gene deletion had no effect on the expression of genes coding for RNases or amino-acyl tRNA synthetases or any other gene among a total of > 1300 genes probed. 2D-PAGE analysis showed that the elaC mutation, like-wise, had no effect on the proteome. These results strengthen doubts about the involvement of E. coli ZiPD in tRNA maturation and suggest functional diversity within the ZiPD/ElaC1 protein family. In addition to these unexpected features of the E. coli elaC deletion mutant, a sequence comparison of ZiPD (ElaC1) proteins revealed specific regions for either enterobacterial or mammalian ZiPD (ElaC1) proteins. PMID:15303284

  10. Temporal Stimulation of Chemotaxis in Escherichia coli

    PubMed Central

    Brown, Douglas A.; Berg, Howard C.

    1974-01-01

    We used the tracking microscope to study the chemotactic responses of E. coli to temporal gradients of L-glutamate generated in isotropic solutions by the action of the enzyme alanine aminotransferase. Positive gradients suppress directional changes which occur spontaneously in the absence of a stimulus. Negative gradients have little effect. The data can be fit with a model in which the suppression is proportional to the time rate of change of the fractional amount of chemoreceptor bound. The model accounts for the behavior of individual cells and populations of cells in spatial gradients. A computer simulation of the motion in spatial gradients indicates that if the bacteria have a “memory,” its decay time cannot be much longer than a few seconds. The relationship between the responses observed in these experiments and in experiments in which solutions of an attractant at different concentrations are mixed is discussed. PMID:4598304

  11. Preparation of Soluble Proteins from Escherichia coli.

    PubMed

    Wingfield, Paul T

    2014-01-01

    Purification of human IL-1? is used in this unit as an example of the preparation of a soluble protein from E. coli. Bacteria containing IL-1? are lysed, and IL-1 ? in the resulting supernatant is purified by anion-exchange chromatography, salt precipitation, and cation-exchange chromatography, and then concentrated. Finally, the IL-1 ? protein is applied to a gel-filtration column to separate it from remaining higher- and lower-molecular-weight contaminants, the purified protein is stored frozen or is lyophilized. The purification protocol described is typical for a protein that is expressed in fairly high abundance (i.e., >5% total protein) and accumulates in a soluble state. In addition, the purification procedure serves as an example of how to use classical protein purifications methods, which may also be used in conjunction with the affinity-based methods now more commonly used. © 2014 by John Wiley & Sons, Inc. PMID:25367009

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

    E-print Network

    Gruenwald, Le

    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

  13. Extensive segments of the Escherichia coli K12 chromosome in Proteus mirabilis diploids

    Microsoft Academic Search

    J. A. Wohlhieter; P. Gemski; L. S. Baron

    1975-01-01

    Various Escherichia coli K12 Hfr donors transfer at low frequency portions of the E. coli genome to Proteus mirabilis. By remating such Proteus hybrids with the same or a different E. coli Hfr strain, other genetic characters could be added to yield diploid Proteus hybrids which contained more than 30% of the E. coli genome. The extent of the E.

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

    Microsoft Academic Search

    Chandra Shekhar Nautiyal; Ateequr Rehman; Puneet Singh Chauhan

    2010-01-01

    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

  15. Closely related strains of Escherichia coli have been shown to cause extraintestinal infections in unrelated per-

    E-print Network

    Boyer, Edmond

    or foodborne transmission in the dissemination of E. coli causing common community-acquired UTIs. Extraintestinal infections caused by Escherichia coli cause serious illness and death. Every year, 6­8 mil- lion related E. coli strains. If there is a food animal reser- voir for extraintestinal E. coli, then the use

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

    PubMed

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

    2010-01-01

    Association of Escherichia coli and enterococci with particulates present in runoff from erodible soils has important implications for modeling the fate and transport of bacteria from agricultural sources and in the selection of management practices to reduce bacterial movement to surface waters. Three soils with different textures were collected from the Ap horizon (silty loam, silty clay loam, and loamy fine sand), placed in portable box plots, treated with standard cowpats, and placed under a rainfall simulator. Rainfall was applied to the plots until saturation-excess flow occurred for 30 min, and samples were collected 10, 20, and 30 min after initiation of the runoff event. The attachment of E. coli and enterococci to particles present in runoff was determined by a screen filtration and centrifugation procedure. Percentage of E. coli and enterococci attached to particulates in runoff ranged from 28 to 49%, with few statistically significant differences in attachment among the three soils. Similar partitioning release patterns were observed between E. coli and enterococci from the silty loam (r = 0.57) and silty clay loam soils (r = 0.60). At least 60% of all attached E. coli and enterococci were associated particles within an 8- to 62-microm particle size category. The results indicate that the majority of fecal bacteria attach to and are transported with manure colloids in sediment-laden flow regardless of the soil texture. PMID:20400597

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

    PubMed

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

    2013-12-01

    Nonthermal atmospheric plasma jet, a promising technology based on ionized gas at low temperatures, can be applied for disinfection of contaminated surfaces. In this study, Escherichia coli cells and their macromolecules were exposed to the nonthermal atmospheric argon plasma jet for different time durations. Total protein, genomic DNA, and malondialdehyde (MDA) levels of E. coli were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining; agarose gel electrophoresis; and measurement of absorbance at 534 nm, respectively. After exposure, the spectroscopic results of liquid samples indicated that the survival reduction of E. coli can reach to 100 % in an exposure time of 600 s. Moreover, inactivation zones of E. coli, DNA degradation, and MDA levels were significantly increased. Additionally, banding patterns of total protein were changed and amino acid concentrations increased following ninhydrin test. The experimental results suggest that the nonthermal plasma could serve as an effective instrument for both sterilizing E. coli and degrading macromolecules from the surface of the objects being sterilized. PMID:23982422

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

    PubMed Central

    Han, Mee-Jung; Lee, Sang Yup

    2006-01-01

    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

  19. Escherichia coli ST131, an Intriguing Clonal Group

    PubMed Central

    Bertrand, Xavier; Madec, Jean-Yves

    2014-01-01

    SUMMARY In 2008, a previously unknown Escherichia coli clonal group, sequence type 131 (ST131), was identified on three continents. Today, ST131 is the predominant E. coli lineage among extraintestinal pathogenic E. coli (ExPEC) isolates worldwide. Retrospective studies have suggested that it may originally have risen to prominence as early as 2003. Unlike other classical group B2 ExPEC isolates, ST131 isolates are commonly reported to produce extended-spectrum ?-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

  20. Recent Advances in Understanding Enteric Pathogenic Escherichia coli

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2012-12-01

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

  2. Selection of Escherichia coli expression systems.

    PubMed

    Bernard, A; Payton, M

    2001-05-01

    This unit lists the most useful expression strains of E. coli for fermentation processes. Standard procedures are provided for several expression systems, namely, temperature induction via the p(L) promoter and chemical induction via the trp promoter, lac or tac promoters, and the T7 promoter. These protocols require that the gene encoding the protein of interest has been identified and cloned into an appropriate expression vector using standard molecular biology techniques. Transformation of a suitable host strain (e.g., by electroporation) is also described and is a prerequisite. Protocols for the analysis of plasmid stability and subsequent storage are provided. Support protocols describe how to prepare samples for electrophoresis, how to analyze the solubility of the expressed proteins, and how to make samples of periplasmic extracts and extracellular media (using TCA precipitation). Many of the support protocols are small-scale analysis procedures that are used to guide subsequent purification strategies and determine the suitability of the expression system for further development and scale-up. PMID:18429183

  3. Widespread antibiotic resistance of diarrheagenic Escherichia coli and Shigella species

    PubMed Central

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

    2014-01-01

    Background: Antibiotic resistance of enteric pathogens particularly Shigella species, is a critical world-wide problem and monitoring their resistant pattern is essential, because the choice of antibiotics is absolutely dependent on regional antibiotic susceptibility patterns. During summer 2013, an unusual increase in number of diarrheal diseases was noticed in Isfahan, a central province of Iran. Therefore, the antibiotic resistance of diarrheagenic Escherichia coli and Shigella species isolated were evaluated. Materials and Methods: According to the guideline on National Surveillance System for Foodborn Diseases, random samples from patients with acute diarrhea were examined in local laboratories of health centers and samples suspicious of Shigella spp. were further assessed in referral laboratory. Isolated pathogens were identified by standard biochemical and serologic tests and antibiotic susceptibility testing was carried out by disc diffusion method. Results: A total of 1086 specimens were obtained and 58 samples suspicious of Shigella were specifically evaluated. The most prevalent isolated pathogen was Shigella sonnei (26/58) followed by E. coli (25/58) and Shigella flexneri (3/58). A large number of isolated bacteria were resistant to co-trimoxazole (Shigella spp: 100%, E. coli: 80%), azithromycin (Shigella spp: 70.4%, E. coli: 44.0%), ceftriaxone (Shigella spp: 88.9%, E. coli: 56.0%) and cefixime (Shigella spp: 85.2%, E. coli: 68.0%). About88.3% of S. sonnei isolates, one S. flexneri isolate, and 56% of E. coli strains were resistant to at least three antibiotic classes (multidrug resistant). Conclusion: Due to high levels of resistance to recommended and commonly used antibiotics for diarrhea, continuous monitoring of antibiotic resistance seems essential for determining best options of empirical therapy. PMID:25002896

  4. coliBASE: an online database for Escherichia coli, Shigella and Salmonella comparative genomics

    PubMed Central

    Chaudhuri, Roy R.; Khan, Arshad M.; Pallen, Mark J.

    2004-01-01

    We have constructed coliBASE, a database for Escherichia coli, Shigella and Salmonella comparative genomics available online at http://colibase.bham.ac.uk. Unlike other E.coli databases, which focus on the laboratory model strain K12, coliBASE is intended to reflect the full diversity of E.coli and its relatives. The database contains comparative data including whole genome alignments and lists of putative orthologous genes, together with numerous analytical tools and links to existing online resources. The data are stored in a relational database, accessible by a number of user-friendly search methods and graphical browsers. The database schema is generic and can easily be applied to other bacterial genomes. Two such databases, CampyDB (for the analysis of Campylobacter spp.) and ClostriDB (for Clostridium spp.) are also available at http://campy.bham.ac.uk and http://clostri.bham.ac.uk, respectively. An example of the power of E.coli comparative analyses such as those available through coliBASE is presented. PMID:14681417

  5. Interactions of Pseudomonas aeruginosa in predominant biofilm or planktonic forms of existence in mixed culture with Escherichia coli in vitro.

    PubMed

    Kuznetsova, Marina V; Maslennikova, Irina L; Karpunina, Tamara I; Nesterova, Larisa Yu; Demakov, Vitaly A

    2013-09-01

    Pseudomonas aeruginosa and Escherichia coli are known to be involved in mixed communities in diverse niches. In this study we examined the influence of the predominant form of cell existence of and the exometabolite production by P. aeruginosa strains on interspecies interactions, in vitro. Bacterial numbers of P. aeruginosa and E. coli in mixed plankton cultures and biofilms compared with their numbers in single plankton cultures and biofilms changed in a different way, but were in accordance with the form of P. aeruginosa cell existence. The mass of a mixed-species biofilm was greater than the mass of a single-species biofilm. Among the mixed biofilms, the one with the "planktonic" P. aeruginosa strain had the least biomass. The total pyocyanin and pyoverdin levels were found to be lower in all mixed plankton cultures. Despite this, clinical P. aeruginosa strains irrespective of the predominant form of existence ("biofilm" or "planktonic") had a higher total concentration of exometabolites than did the reference strain in 12-24 h mixed cultures. The metabolism of E. coli, according to its bioluminescence, was reduced in mixed cultures, and the decrease was by 20- to 100-fold greater with the clinical Pseudomonas strains than the reference Pseudomonas strain. Thus, both the predominant form of existence of and the exometabolite production by distinct P. aeruginosa strains should be considered to fully understand the interspecies relationship and bacteria survival in natural communities. PMID:24011343

  6. Studies on the Chick-lethal Toxin of Escherichia coli

    PubMed Central

    Truscott, R. B.

    1973-01-01

    A toxin which is lethal for two week old chicks has been recovered from strains of Escherichia coli O78:K80 of bovine and avian origin and from avian isolates of serogroups O2, O45 and O109. The toxin is heat-labile, antigenic, high in protein, inactivated by pronase, trypsin, amylase, and pancreatic lipase. The toxin may be precipitated by ammonium sulfate or TCA treatment from the supernatant obtained by repeated centrifugation of sonicated cells. Considerable purification has been obtained by column chromatography using Sepharose 6B. PMID:4270809

  7. Ribosomal crystalline arrays of large subunits from Escherichia coli.

    PubMed

    Clark, M W; Leonard, K; Lake, J A

    1982-05-28

    Crystalline sheets of the 50S ribosomal subunits of Escherichia coli have been formed in vitro. Electron micrographs of these arrays diffract to 35-angstrom resolution. The lattice parameters of the crystals are a = 330 +/- 20 angstroms, b = 330 +/- 30 angstroms, and alpha = 123 degrees +/- 5 degrees, and the space group is most likely p21. These arrays of ribosomal subunits are sufficiently ordered to resolve such known features of the large ribosomal subunit as the L7/L12 stalk and the central protuberance. PMID:7043735

  8. Biochemical and cultural characteristics of invasive Escherichia coli.

    PubMed Central

    Silva, R M; Toledo, M R; Trabulsi, L R

    1980-01-01

    The biochemical characteristics of 97 invasive Escherichia coli strains of different O serogroups were studied. Considered as a group, the behavior of the strains was quite variable. However, none of them decarboxylated lysine and all but seven strains, belonging to the O124 serogroup, were nonmotile. The growth of 25 strains obtained on MacConkey, salmonella-shigella, xylose-lysine-desoxycholate, and Hektoen enteric agars was compared. MacConkey and Hektoen enteric agars yielded the highest average growth for these strains, whereas salmonella-shigella agar had the lowest average counts. PMID:6991526

  9. L Tyrosine production by deregulated strains of Escherichia coli

    Microsoft Academic Search

    Tina Lütke-Eversloh; Gregory Stephanopoulos

    2007-01-01

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

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

    PubMed Central

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

    1989-01-01

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

  11. Genome-scale genetic engineering in Escherichia coli.

    PubMed

    Jeong, Jaehwan; Cho, Namjin; Jung, Daehee; Bang, Duhee

    2013-11-01

    Genome engineering has been developed to create useful strains for biological studies and industrial uses. However, a continuous challenge remained in the field: technical limitations in high-throughput screening and precise manipulation of strains. Today, technical improvements have made genome engineering more rapid and efficient. This review introduces recent advances in genome engineering technologies applied to Escherichia coli as well as multiplex automated genome engineering (MAGE), a recent technique proposed as a powerful toolkit due to its straightforward process, rapid experimental procedures, and highly efficient properties. PMID:23624241

  12. Crystal structure of GnsA from Escherichia coli.

    PubMed

    Wei, Yong; Zhan, Lihong; Gao, Zengqiang; Privé, Gilbert G; Dong, Yuhui

    2015-06-19

    Escherichia Coli GnsA is a regulator of phosphatidylethanolamine synthesis and functions as a suppressor of both a secG null mutation and fabA6 mutations. GnsA may also be a toxin with the cognate antitoxin YmcE. Here we report the crystal structure of GnsA to 1.8 Å. GnsA forms a V shaped hairpin structure that is tightly associated into a homodimer. Our comprehensive structural study suggests that GnsA is structurally similar to an outer membrane protein, suggesting a function of protein binding. PMID:25839658

  13. Molecular Evolution of the Escherichia Coli Chromosome. III. Clonal Frames

    PubMed Central

    Milkman, R.; Bridges, M. M.

    1990-01-01

    PCR fragments, 1500-bp, from 15 previously sequenced regions in the Escherichia coli chromosome have been compared by restriction analysis in a large set of wild (ECOR) strains. Prior published observations of segmental clonality are confirmed: each of several sequence types is shared by a number of strains. The rate of recombinational replacement and the average size of the replacements are estimated in a set of closely related strains in which a clonal frame is dotted with occasional stretches of DNA belonging to other clones. A clonal hierarchy is described. Some new comparative sequencing data are presented. PMID:1979037

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

    PubMed

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

    2008-10-01

    Hemolytic uremic syndrome (HUS) is characterized by microangiopathic hemolytic anemia, plaquetopenia and kidney damage. It is the leading cause of acute renal failure in pediatric age and the second for chronic renal failure. Shiga toxin-producing Escherichia coli (STEC) is the first etiologic agent of HUS being its main reservoir cattle and transmitted via contaminated food. At present, there is no specific treatment to reduce the progression of HUS. The study of the mechanisms by which STEC infects and Shiga toxin induces HUS can help to find new strategies to prevent this disease. PMID:19030644

  15. Genetic characterization of moaB mutants of Escherichia coli.

    PubMed

    Kozmin, Stanislav G; Schaaper, Roel M

    2013-09-01

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

  16. Global Analysis of Extracytoplasmic Stress Signaling in Escherichia coli

    PubMed Central

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

    2009-01-01

    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

  17. Stringent control of peptidoglycan biosynthesis in Escherichia coli K-12.

    PubMed Central

    Ishiguro, E E; Ramey, W D

    1976-01-01

    [3H]Diaminopimelic acid (Dap) was incorporated exclusively into peptidoglycan by Escherichia coli strains auxotrophic for both lysine and Dap. The rate of [3H]Dap incorporation by stringent (rel+) strains was significantly decreased when cells were deprived of required amino acids. The addition of chloramphenicol to amino acid-starved rel+ cultured stimulated both peptidoglycan and ribonucleic acid synthesis. In contrast, a relaxed (relA) derivative incorporated [3H]Dap at comparable rates in the presence or absence of required amino acids. Physiologically significant concentrations of guanosine 5'-diphosphate 3'-diphosphate (ppGpp) inhibited the in vitro synthesis of both carrier lipid-linked intermediate and peptidoglycan catalyzed by a particulate enzyme system. The degree of inhibition was dependent on the concentration of ppGpp in the reaction mixture. Thus, the results of in vivo and in vitro studies indicate that peptidoglycan synthesis is stringently controlled in E. coli. PMID:783130

  18. Biocatalytically active silCoat-composites entrapping viable Escherichia coli.

    PubMed

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

    2014-02-01

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

  19. Splenic abscess: Plasmodium vivax with secondary Escherichia coli infection.

    PubMed

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

    2015-04-01

    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

  20. Chelocardin-Inducible Resistance in Escherichia coli Bearing R Plasmids

    PubMed Central

    Chabbert, Yves A.; Scavizzi, Maurice R.

    1976-01-01

    Two plasmid-linked tetracycline resistance characters, tet A and tet B, were distinguishable in part, according to the level of resistance they conferred to minocycline (<3 ?g/ml for tet A; >6 ?g/ml for tet B). Escherichia coli K-12 strains that harbored the tet B character were also resistant to tetracycline but susceptible to chelocardin. In such tet B strains, subinhibitory concentrations of tetracycline could induce resistance to chelocardin as well as to otherwise inhibitory concentrations of tetracyclines. Chelocardin itself was ineffective as an inducer and therefore could be used to select constitutively resistant mutants. E. coli K-12 strains harboring the tet A character were also resistant to tetracycline and susceptible to chelocardin; tetracycline did not induce resistance to chelocardin in these strains. Images PMID:769671

  1. Escherichia coli and Community-acquired Gastroenteritis, Melbourne, Australia

    PubMed Central

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

    2004-01-01

    As part of a study to determine the effects of water filtration on the incidence of community-acquired gastroenteritis in Melbourne, Australia, we examined fecal samples from patients with gastroenteritis and asymptomatic persons for diarrheagenic strains of Escherichia coli. Atypical strains of enteropathogenic E. coli (EPEC) were the most frequently identified pathogens of all bacterial, viral, and parasitic agents in patients with gastroenteritis. Moreover, atypical EPEC were more common in patients with gastroenteritis (89 [12.8%] of 696) than in asymptomatic persons (11 [2.3%] of 489, p < 0.0001). Twenty-two random isolates of atypical EPEC that were characterized further showed marked heterogeneity in terms of serotype, genetic subtype, and carriage of virulence-associated determinants. Apart from the surface protein, intimin, no virulence determinant or phenotype was uniformly present in atypical EPEC strains. This study shows that atypical EPEC are an important cause of gastroenteritis in Melbourne. PMID:15504266

  2. Atypical Enteropathogenic Escherichia coli Infection and Prolonged Diarrhea in Children

    PubMed Central

    Nguyen, Rang N.; Taylor, Louise S.; Tauschek, Marija

    2006-01-01

    Some clinical isolates of enteropathogenic Escherichia coli (EPEC) lack bundle-forming pili and are termed atypical EPEC. The aim of this study was to determine if atypical EPEC are pathogens by comparing the clinical features of patients infected with atypical EPEC with those of children infected with other causative agents of diarrhea. Fecal samples obtained from children attending the Royal Children's Hospital in Melbourne for investigation of diarrhea were examined for adenovirus, rotavirus, Campylobacter spp., Salmonella spp., protozoa, and pathogenic E. coli. Clinical data were obtained by using a standardized pro forma and analyzed separately. Patients infected with atypical EPEC experienced mild, nondehydrating, and noninflammatory diarrhea that was not particularly associated with fever, vomiting, or abdominal pain. However, the duration of diarrhea in patients infected with atypical EPEC was significantly longer than that caused by the other species or where no pathogens were identified. Infection with atypical EPEC is associated with prolonged diarrhea. PMID:16704807

  3. Escherichia coli response to exogenous pyrophosphate and analogs.

    PubMed

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

    2003-01-01

    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

  4. Mounting of Escherichia coli spheroplasts for AFM imaging.

    SciTech Connect

    Sullivan, Claretta J [ORNL; Morrell-Falvey, Jennifer L [ORNL; Allison, David P [ORNL; Doktycz, Mitchel John [ORNL

    2005-11-01

    The cytoplasmic membrane of Escherichia coli (E. coli) is the location of numerous, chemically specific transporters and recognition elements. Investigation of this membrane in vivo by atomic force microscopy (AFM) requires removal of the cell wall and stable immobilization of the spheroplast. AFM images demonstrate that spheroplasts can be secured with warm gelatin applied to the mica substrate just before the addition of a spheroplast suspension. The resulting preparation can be repeatedly imaged by AFM over the course of several hours. Confocal fluorescence imaging confirms the association of the spheroplasts with the gelatin layer. Gelatin molecules are known to reorder into a network after heating. Entrapment within this gelatin network is believed to be responsible for the immobilization of spheroplasts on mica.

  5. Engineered polyketide biosynthesis and biocatalysis in Escherichia coli

    PubMed Central

    Gao, Xue; Wang, Peng

    2010-01-01

    Polyketides are important bioactive natural products biosynthesized by bacteria, fungi, and plants. The enzymes that synthesize polyketides are collectively referred to as polyketide synthases (PKSs). Because many of the natural hosts that produce polyketides are difficult to culture or manipulate, establishing a universal heterologous host that is genetically tractable has become an important goal toward the engineered biosynthesis of polyketides and analogues. Here, we summarize the recent progresses in engineering Escherichia coli as a heterologous host for reconstituting PKSs of different types. Our increased understanding of PKS enzymology and structural biology, combined with new tools in protein engineering, metabolic engineering, and synthetic biology, has firmly established E. coli as a powerful host for producing polyketides. PMID:20853106

  6. Heterologous biosynthesis of costunolide in Escherichia coli and yield improvement.

    PubMed

    Yin, Hua; Zhuang, Yi-Bin; Li, E-E; Bi, Hui-Ping; Zhou, Wei; Liu, Tao

    2015-06-01

    Costunolide, the main bioactive compound of the medicinal plant, Radix Aucklandiae, is a sesquiterpene lactone (SL) and has a broad range of biological activities. It is also a precursor of many biologically-active SLs and is a branching point in the biosynthesis of SLs. Here we have reconstituted the costunolide biosynthetic pathway in Escherichia coli by co-expression of three genes (GAS, GAO, LsCOS) involved in costunolide biosynthesis and eight genes involved in converting acetyl-CoA into farnesyl diphosphate from mevalonate pathway. Costunolide production was then detected. By screening and optimization of cultured medium and inducing temperature, costunolide yield was up to 100 mg l(-1) in E. coli. PMID:25700819

  7. Cellulosic hydrolysate toxicity and tolerance mechanisms in Escherichia coli

    PubMed Central

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

    2009-01-01

    The sustainable production of biofuels will require the efficient utilization of lignocellulosic biomass. A key barrier involves the creation of growth-inhibitory compounds by chemical pretreatment steps, which ultimately reduce the efficiency of fermentative microbial biocatalysts. The primary toxins include organic acids, furan derivatives, and phenolic compounds. Weak acids enter the cell and dissociate, resulting in a drop in intracellular pH as well as various anion-specific effects on metabolism. Furan derivatives, dehydration products of hexose and pentose sugars, have been shown to hinder fermentative enzyme function. Phenolic compounds, formed from lignin, can disrupt membranes and are hypothesized to interfere with the function of intracellular hydrophobic targets. This review covers mechanisms of toxicity and tolerance for these compounds with a specific focus on the important industrial organism Escherichia coli. Recent efforts to engineer E. coli for improved tolerance to these toxins are also discussed. PMID:19832972

  8. Expression of a proline-enriched protein in Escherichia coli

    SciTech Connect

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

    1982-03-01

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

  9. Structural and Biochemical Characterization of a Quinol Binding Site of Escherichia coli Nitrate Reductase A*

    E-print Network

    Strynadka, Natalie

    Structural and Biochemical Characterization of a Quinol Binding Site of Escherichia coli Nitrate of Escherichia coli nitrate re- ductase A (NarGHI) in complex with pentachlorophenol has been determined to 2.0 Å of resolution. We have shown that pentachlorophenol is a potent inhibitor of quinol:nitrate oxidoreductase

  10. Virulence factors, Serotypes and Antimicrobial Suspectibility Pattern of Escherichia coli in Urinary Tract Infections

    Microsoft Academic Search

    Yasmeen Kausar; Sneha K Chunchanur; Shobha D Nadagir; LH Halesh; M R Chandrasekhar

    Purpose: To study the virulence factors, serotypes of uropathogenic Escherichia coli (UPEC) and antimicrobial suspectibility pattern. Methods: A total of 200 Escherichia coli from symptomatic cases of urinary tract infections and 50 stool samples from apparently healthy individuals were included. UPEC were screened for virulence factors namely haemolysin, mannose resistant, mannose sensitive haemagglutination (MRHA, MSHA) and serum resistance by recommended

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

    Microsoft Academic Search

    2006-01-01

    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

  12. Review article Escherichia coli as a pathogen in dogs and cats

    E-print Network

    Paris-Sud XI, Université de

    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

  13. Escherichia coli maltose-binding protein is uncommonly effective at promoting the solubility

    E-print Network

    Escherichia coli maltose-binding protein is uncommonly effective at promoting the solubility of a recombinant protein in Escherichia coli, obtaining the protein in a soluble, biologically active form-prone polypeptide to a highly soluble partner. To study this phenomenon in greater detail, we compared the ability

  14. Structure of the Heme d of Penicillium vitale and Escherichia coli Catalases*

    E-print Network

    Structure of the Heme d of Penicillium vitale and Escherichia coli Catalases* (Received-hydroxychlorin -spirolactone has been found in the crystal structures of Penicillium vitale catalase and Escherichia coli catalase hydroperoxidase II (HPII). The absolute stereochemistry of the two heme d chiral car- bon atoms

  15. Enhanced Hydrogen Production in Escherichia coli Through Chemical Mutagenesis, Gene Deletion, and Transposon Mutagenesis

    E-print Network

    Garzon Sanabria, Andrea Juliana

    2011-08-08

    ENHANCED HYDROGEN PRODUCTION IN ESCHERICHIA COLI THROUGH CHEMICAL MUTAGENESIS, GENE DELETION, AND TRANSPOSON MUTAGENESIS A Thesis by ANDREA JULIANA GARZON SANABRIA Submitted to the Office of Graduate Studies of Texas A...&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 2010 Major Subject: Chemical Engineering ENHANCED HYDROGEN PRODUCTION IN ESCHERICHIA COLI THROUGH CHEMICAL MUTAGENESIS, GENE DELETION...

  16. SHORT REPORT Open Access Escherichia coli BdcA controls biofilm dispersal in

    E-print Network

    Wood, Thomas K.

    SHORT REPORT Open Access Escherichia coli BdcA controls biofilm dispersal in Pseudomonas aeruginosa that BdcA controls Escherichia coli biofilm dispersal by binding the ubiquitous bacterial signal cyclic by increasing motility, decreasing aggregation, and decreasing production of biofilm adhesins. Findings: Here we

  17. A generic protocol for the expression and purification of recombinant proteins in Escherichia coli using a

    E-print Network

    A generic protocol for the expression and purification of recombinant proteins in Escherichia coli for the overproduction and purification of recombinant proteins in Escherichia coli. The strategy utilizes a dual His6 the yield and solubility of the target protein; and (iii) the large-scale production and purification

  18. Research review paper Genome-scale genetic engineering in Escherichia coli

    E-print Network

    Bang, Duhee

    Research review paper Genome-scale genetic engineering in Escherichia coli Jaehwan Jeong 1 , Namjin cells. Escherichia coli has been a particularly good model organism for bac- terial genome engineering Keywords: Genome engineering Red recombination Multiplex automated genome engineering Genome engineering

  19. Functional Interrelationships in the Alkaline Phosphatase Superfamily: Phosphodiesterase Activity of Escherichia coli Alkaline Phosphatase

    E-print Network

    Herschlag, Dan

    Functional Interrelationships in the Alkaline Phosphatase Superfamily: Phosphodiesterase Activity of Escherichia coli Alkaline Phosphatase Patrick J. O'Brien and Daniel Herschlag* Department of BiochemistryVised Manuscript ReceiVed March 15, 2001 ABSTRACT: Escherichia coli alkaline phosphatase (AP) is a proficient

  20. The MukF subunit of Escherichia coli condensin: architecture and functional relationship to kleisins

    E-print Network

    Berger, James M.

    The MukF subunit of Escherichia coli condensin: architecture and functional relationship to kleisins Rachel Fennell-Fezzie, Scott D Gradia, David Akey and James M Berger* Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA The Escherichia coli MukB, MukE, and MukF

  1. Adhesive Escherichia coli in inflammatory bowel disease and infective diarrhoea.

    PubMed Central

    Burke, D. A.; Axon, A. T.

    1988-01-01

    The clinical features of ulcerative colitis and Crohn's disease are similar to those of infections of the bowel, although their cause is uncertain. Many bacteria that cause intestinal diseases adhere to the gut mucosa, and adhesion of pathogenic Escherichia coli is resistant to D-mannose. The adhesive properties of isolates of E coli were assessed by assay of adhesion to buccal epithelial cells with mannose added. The isolates were obtained from patients with inflammatory bowel diseases (50 with a relapse of ulcerative colitis, nine with ulcerative colitis in remission, 13 with Crohn's disease, and 11 with infectious diarrhoea not due to E coli) and 22 controls. The median index of adhesion to buccal epithelial cells (the proportion of cells with more than 50 adherent bacteria) for E coli from patients with ulcerative colitis in relapse was significantly higher (43%) than that for controls (5%) and patients with infectious diarrhoea (14%). The index was not significantly different among isolates from patients with ulcerative colitis in relapse, Crohn's disease (53%), and ulcerative colitis in remission (30%). If an index of adhesion of greater than 25% is taken as indicating an adhesive strain 86% of isolates of E coli from patients with inflammatory bowel disease were adhesive compared with 27% from patients with infective diarrhoea and none from controls. The adhesive properties of the isolates from patients with inflammatory bowel disease were similar to those of pathogenic intestinal E coli, raising the possibility that they may have a role in the pathogenesis of the condition; the smaller proportion of adhesive isolates in patients with infective diarrhoea due to other bacteria suggests that the organism may be of primary importance rather than arising secondarily. Images a PMID:3044496

  2. Emergence of imipenem resistance in clinical Escherichia coli during therapy.

    PubMed

    Oteo, Jesús; Delgado-Iribarren, Alberto; Vega, Dolores; Bautista, Verónica; Rodríguez, María Cruz; Velasco, María; Saavedra, José María; Pérez-Vázquez, María; García-Cobos, Silvia; Martínez-Martínez, Luis; Campos, José

    2008-12-01

    The molecular epidemiology and the mechanisms of resistance of Escherichia coli isolated from two patients infected by imipenem-resistant strains are reported in this study. From one patient, three closely related consecutive isolates of E. coli were recovered; the first was carbapenem-susceptible but acquired imipenem resistance after treatment with ertapenem, and the third isolate was again imipenem-susceptible. An additional imipenem-resistant isolate was recovered from another patient who received imipenem. The genetic relatedness of the E. coli isolates was determined by pulsed-field gel electrophoresis (PFGE) after digestion with XbaI. Standard polymerase chain reaction (PCR) conditions were used to amplify several beta-lactamase genes coding for carbapenemases, extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC; the E. coli ampC gene promoter was also amplified and sequenced. Primers OmpF-F/OmpF-R and OmpC-F/OmpC-R were used to amplify the ompF and ompC genes. The outer membrane protein (OMP) profiles were studied by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Imipenem-resistant E. coli isolates did not produce carbapenemases but lacked the two major OMPs OmpF and OmpC and had ampC promoter mutations; in addition, one of the imipenem-resistant isolates produced the CMY-2 cephalosporinase, whilst the other produced the new CTX-M-67 ESBL. Carbapenem resistance in this study was associated with lack of expression of OmpF and OmpC porins. Additional mechanisms of beta-lactam resistance, such as plasmid-mediated AmpC and ESBL production, were also found. Development of carbapenem resistance in a CTX-M-67-producing E. coli is first described in this study. PMID:18775649

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

    PubMed Central

    2013-01-01

    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

  4. Engineered isoprenoid pathway enhances astaxanthin production in Escherichia coli.

    PubMed

    Wang, C W; Oh, M K; Liao, J C

    1999-01-20

    The isoprenoid pathway is a versatile biosynthetic network leading to over 23,000 compounds. Similar to other biosynthetic pathways, the production of isoprenoids in microorganisms is controlled by the supply of precursors, among other factors. To engineer a host that has the capability to supply geranylgeranyl diphosphate (GGPP), a common precursor of isoprenoids, we cloned and overexpressed isopentenyl diphosphate (IPP) isomerase (encoded by idi) from Escherichia coli and GGPP synthase (encoded by gps) from the archaebacterium Archaeoglobus fulgidus. The latter was shown to be a multifunctional enzyme converting dimethylallyl diphosphate (DMAPP) to GGPP. These two genes and the gene cluster (crtBIYZW) of the marine bacterium Agrobacterium aurantiacum were introduced into E. coli to produce astaxanthin, an orange pigment and antioxidant. This metabolically engineered strain produces astaxanthin 50 times higher than values reported before. To determine the rate-controlling steps in GGPP production, the IDI-GPS pathway was compared with another construct containing idi, ispA (encoding farnesyl diphosphate (FPP) synthase in E. coli), and crtE (encoding GGPP synthase from Erwinia uredovora). Results show that the conversion from FPP to GGPP is the first bottleneck, followed sequentially by IPP isomerization and FPP synthesis. Removal of these bottlenecks results in an E. coli strain providing sufficient precursors for in vivo synthesis of isoprenoids. PMID:10099534

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

    PubMed Central

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

    2010-01-01

    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

  6. Low intensity infrared laser induces filamentation in Escherichia coli cells

    NASA Astrophysics Data System (ADS)

    Fonseca, A. S.; Presta, G. A.; Geller, M.; Paoli, F.

    2011-10-01

    Low intensity continuous wave and pulsed emission modes laser is used in treating many diseases and the resulting biostimulative effect on tissues has been described, yet the photobiological basis is not well understood. The aim of this wok was to evaluate, using bacterial filamentation assay, effects of laser on Escherichia coli cultures in exponential and stationary growth phase. E. coli cultures, proficient and deficient on DNA repair, in exponential and stationary growth phase, were exposed to low intensity infrared laser, aliquots were spread onto microscopic slides, stained by Gram method, visualized by optical microscopy, photographed and percentage of bacterial filamentation were determined. Low intensity infrared laser with therapeutic fluencies and different emission modes can induce bacterial filamentation in cultures of E. coli wild type, fpg/ mutM, endonuclease III and exonuclease III mutants in exponential and stationary growth phase. This study showed induction of bacterial, filamentation in E. coli cultures expose to low intensity infrared laser and attention to laser therapy protocols, which should take into account fluencies, wavelengths, tissue conditions, and genetic characteristics of cells before beginning treatment.

  7. Magnetically-Actuated Escherichia coli System for Micro Lithography

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  8. Dynamic Transcriptional Response of Escherichia coli to Inclusion Body Formation

    PubMed Central

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

    2014-01-01

    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

  9. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Escherichia coli O157:H7 specific bacteriophages...Tolerances § 180.1301 Escherichia coli O157:H7 specific bacteriophages...bacteriophages that are specific to Escherichia coli O157:H7,...

  10. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Escherichia coli O157:H7 specific bacteriophages...Tolerances § 180.1301 Escherichia coli O157:H7 specific bacteriophages...bacteriophages that are specific to Escherichia coli O157:H7,...

  11. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  13. Evaluation of the antibacterial activity of cystatin against selected strains of Escherichia coli.

    PubMed

    Szpak, Maciej; Trziszka, Tadeusz; Polanowski, Antoni; Gburek, Jakub; Go??b, Krzysztof; Juszczy?ska, Katarzyna; Janik, Paulina; Malicki, Adam; Szyplik, Katarzyna

    2014-01-01

    The aim of this study was to analyze the antibacterial activity of hen egg white cystatin against selected Escherichia coli strains. We used a monomeric solution of hen egg white cystatin in bovine serum albumin (BSA) with added phosphate buffered saline (PBS), and three test strains: Escherichia coli ATCC 23811, Escherichia coli ATCC 8739 and Escherichia coli ATCC 25922. The effect of cystatin against the tested strains was determined on the basis of minimal inhibitory concentration (MIC) and survival curves of the microorganisms in a cystatin-containing environment during incubation at various temperatures. Our study confirmed the activity of cystatin against the analyzed Escherichia coli strains. taining environment, as compared to control samples incubated in a ovocystatin-deficient medium. Depending on the incubation temperature (20 degrees C or 37 degrees C) the reduction persisted up to 12 hours after incubation. PMID:25403072

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

    Microsoft Academic Search

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

    2005-01-01

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

  15. Enhanced ?-aminobutyric acid-forming activity of recombinant glutamate decarboxylase (gadA) from Escherichia coli

    Microsoft Academic Search

    Qi WangYinqiang; Yinqiang Xin; Feng Zhang; Zhiyong Feng; Jin Fu; Lan Luo; Zhimin Yin

    2011-01-01

    ?-aminobutyric acid (GABA) is an important bioactive regulator, and its biosynthesis is primarily through the ?-decarboxylation of glutamate by glutamate decarboxylase (GAD). The procedures to obtain GABA by bioconvertion with high activity\\u000a recombinant Escherichia coli GAD have been seldom understood. In this study, Escherichia coli GAD (gadA) was highly expressed (about 70–75% of total protein) as soluble protein in Escherichia

  16. Atypical enteropathogenic Escherichia coli secretes plasmid encoded toxin.

    PubMed

    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

    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

  17. Atypical Enteropathogenic Escherichia coli Secretes Plasmid Encoded Toxin

    PubMed Central

    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

    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

  18. Codon Optimisation Is Key for Pernisine Expression in Escherichia coli

    PubMed Central

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

    2015-01-01

    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

  19. Nucleotide sequence of an Escherichia coli chromosomal hemolysin.

    PubMed Central

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

    1985-01-01

    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

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

    PubMed Central

    Mergeay, M; Gerits, J

    1978-01-01

    Various F' plasmids of Escherichia coli K-12 could be transferred into mutants of the soil strain 6.2, classified herein as a Pseudomonas fluorescens biotype IV. This strain was previously found to receive Flac plasmid (N. Datta and R.W. Hedges, J. Gen Microbiol. 70:453-460, 1972). ilv, leu, met, arg, and his auxotrophs were complemented by plasmids carrying isofunctional genes; trp mutants were not complemented or were very poorly complemented. The frequency of transfer was 10(-5). Subsequent transfer into other P. fluorescens recipients was of the same order of magnitude. Some transconjugants were unable to act as donors, and these did not lose the received information if subcultured on nonselective media. Use of F' plasmids helped to discriminate metabolic blocks in P. fluorescens. In particular, metA, metB, and argH mutants were so distinguished. In addition, F131 plasmid carrying the his operon and a supD mutation could partially relieve the auxotrophy of thr, ilv, and metA13 mutants, suggesting functional expression of E. coli tRNA in P. fluorescens. In P. fluorescens metA Rifr mutants carrying the F110 plasmid, which carried the E. coli metA gene and the E. coli rifs allele, sensitivity to rifampin was found to be dominant at least temporarily over resistance. This suggests interaction of E. coli and P. fluorescens subunits of RNA polymerase. his mutations were also complemented by composite P plasmids containing the his-nif region of Klebsiella pneumoniae (plasmids FN68 and RP41). nif expression could be detected by acetylene reduction in some his+ transconjugants. The frequency of transfer of these P plasmids was 5 X 10(-4). PMID:97267

  1. The asymptomatic bacteriuria Escherichia coli strain 83972 outcompetes uropathogenic E. coli strains in human urine.

    PubMed

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

    2006-01-01

    Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract. The prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. Deliberate colonization of UTI-susceptible individuals with E. coli 83972 has been used successfully as an alternative approach for the treatment of patients who are refractory to conventional therapy. Colonization with strain 83972 appears to prevent infection with UPEC strains in such patients despite the fact that this strain is unable to express the primary adhesins involved in UTI, viz. P and type 1 fimbriae. Here we investigated the growth characteristics of E. coli 83972 in human urine and show that it can outcompete a representative spectrum of UPEC strains for growth in urine. The unique ability of ABU E. coli 83972 to outcompete UPEC in urine was also demonstrated in a murine model of human UTI, confirming the selective advantage over UPEC in vivo. Comparison of global gene expression profiles of E. coli 83972 grown in lab medium and human urine revealed significant differences in expression levels in the two media; significant down-regulation of genes encoding virulence factors such as hemolysin, lipid A, and capsular polysaccharides was observed in cells grown in urine. Clearly, divergent abilities of ABU E. coli and UPEC to exploit human urine as a niche for persistence and survival suggest that these key differences may be exploited for preventative and/or therapeutic approaches. PMID:16369018

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

    PubMed Central

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

    2006-01-01

    Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract. The prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. Deliberate colonization of UTI-susceptible individuals with E. coli 83972 has been used successfully as an alternative approach for the treatment of patients who are refractory to conventional therapy. Colonization with strain 83972 appears to prevent infection with UPEC strains in such patients despite the fact that this strain is unable to express the primary adhesins involved in UTI, viz. P and type 1 fimbriae. Here we investigated the growth characteristics of E. coli 83972 in human urine and show that it can outcompete a representative spectrum of UPEC strains for growth in urine. The unique ability of ABU E. coli 83972 to outcompete UPEC in urine was also demonstrated in a murine model of human UTI, confirming the selective advantage over UPEC in vivo. Comparison of global gene expression profiles of E. coli 83972 grown in lab medium and human urine revealed significant differences in expression levels in the two media; significant down-regulation of genes encoding virulence factors such as hemolysin, lipid A, and capsular polysaccharides was observed in cells grown in urine. Clearly, divergent abilities of ABU E. coli and UPEC to exploit human urine as a niche for persistence and survival suggest that these key differences may be exploited for preventative and/or therapeutic approaches. PMID:16369018

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

    PubMed

    Shi, Hui-Qing; Sun, Feng-Jun; Chen, Jian-Hong; Yong, Xiao-Lan; Ou, Qian-Yi; Feng, Wei; Xia, Pei-Yuan

    2014-11-01

    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

  4. 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

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

    2014-01-01

    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

  5. Some evidences on the mode of action of Cinnamomum verum bark essential oil, alone and in combination with piperacillin against a multi-drug resistant Escherichia coli strain.

    PubMed

    Yap, Polly Soo Xi; Krishnan, Thiba; Chan, Kok-Gan; Lim, Swee Hua Erin

    2014-11-10

    The purpose of this study was to investigate the mode of action of the cinnamon bark essential oil (CB) when use singly and in combination with piperacillin on its antimicrobial and synergistic activity against plasmid-conferred multi-drug resistant Escherichia coli J53 R1. Viable count of this combination showed a complete killing profile at 20 h and further confirmed its synergistic effect by reducing the bacteria cell numbers. Analysis of the membrane permeabilizing effects of CB on treated cultures through their stability against sodium dodecyl sulfate (SDS) revealed that the essential oils played a role in disrupting the bacterial cell membrane. Scanning electron microscopy analysis and zeta potential measurement also revealed that CB causes irreversible membrane damage and reduces the bacterial surface charge. In addition, reduction in bioluminescence expression of Escherichia coli [pSB1075] and E. coli [pSB401] by CB showed the presence of potential quorum sensing (QS) inhibitors. Gas-chromatography and mass spectrometry (GC-MS) of the essential oil of Cinnamomum verum showed that trans-cinnamaldehyde (72.81%), benzyl alcohol (12.5%) and eugenol (6.57%) were found to be the major components in the essential oil. These findings suggest that CB has the potential to reverse bacteria resistance to piperacillin in E. coli J53 R1 and may operate via two mechanisms: alteration of outer membrane permeability and inhibition of bacterial QS. PMID:25381741

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

    Microsoft Academic Search

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

    2005-01-01

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

  7. Mouse in vivo neutralization of Escherichia coli Shiga toxin 2 with monoclonal antibodies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli (E. coli) food contaminations pose serious health and food safety concerns, and have been the subject of massive food recalls. Shiga toxin 2 (Stx2)-producing E. coli has been identified as the major cause of hemorrhagic colitis and hemolytic uremic syndrome (HUS), the most severe di...

  8. 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...

  9. A glimpse of Escherichia coli O157:H7 survival in soils from eastern China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli O157:H7 (E. coli O157:H7) is an important food-borne pathogen, which continues to be a major public health concern worldwide. It is known that E. coli O157:H7 survive in soil environment might result in the contamination of fresh produce or water source. To investigate how the soils...

  10. Resistance of various shiga toxin-producing Escherichia coli to electrolyzed oxidizing water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The resistance of thirty two strains of Escherichia coli O157:H7 and six major serotypes of non-O157 Shiga toxin- producing E. coli (STEC) plus E. coli O104 was tested against Electrolyzed oxidizing (EO) water using two different methods; modified AOAC 955.16 sequential inoculation method and minim...

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

    PubMed

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

    2015-01-01

    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

  12. 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 ...

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

    Microsoft Academic Search

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

    2009-01-01

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

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

    ERIC Educational Resources Information Center

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

    2004-01-01

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

  15. Comparison of the Small Molecule Metabolic Enzymes of Escherichia coli and Saccharomyces cerevisiae

    Microsoft Academic Search

    Oliver Jardine; Julian Gough; Cyrus Chothia; Sarah A. Teichmann

    2002-01-01

    The comparison of the small molecule metabolism pathways in Escherichia coli and Saccharomyces cerevisiae (yeast) shows that 271 enzymes are common to both organisms. These common enzymes involve 384 gene products in E. coli and 390 in yeast, which are between one half and two thirds of the gene products of small molecule metabolism in E. coli and yeast, respectively.

  16. 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...

  17. Phenotypic and genotypic antimicrobial resistance patterns of Escherichia coli isolated from dairy cows with mastitis

    Microsoft Academic Search

    Velusamy Srinivasan; Barbara E. Gillespie; Mark J. Lewis; Lien T. Nguyen; Susan I. Headrick; Ynte H. Schukken; Stephen P. Oliver

    2007-01-01

    Pulsed field gel electrophoresis (PFGE) patterns, susceptibility to 26 antimicrobial agents used in veterinary and human medicine, and prevalence of antimicrobial resistance genes of Escherichia coli isolated from cows with mastitis were evaluated. Among 135 E. coli isolates, PFGE analysis revealed 85 different genetic patterns. All E. coli were resistant to two or more antimicrobials in different combinations. Most E.

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

    Microsoft Academic Search

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

    2007-01-01

    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,

  19. Escherichia coli diversity in the lower intestinal tract of humans.

    PubMed

    Gordon, David M; O'Brien, Claire L; Pavli, Paul

    2015-08-01

    Previous studies examining the clonal diversity of Escherichia coli populations within humans have been based on faecal isolates. In this study E.?coli were isolated from biopsies taken from the terminal ileum, ascending, transverse and descending colon, and rectum of 69 individuals. Multiple isolates from each biopsy were characterized using Rep-PCR. An average of 3.5 genotypes were recovered per host, and in hosts with two or more strains, the phylogroup membership of the second most abundant strain was significantly more likely to be the same as the dominant strain. There was no indication of a non-random distribution of E.?coli phylogroups among the regions of the lower intestine. In hosts with multiple genotypes, as defined by Repetitive extragenic palindromic-PCR, genotypes were non-randomly distributed among gut regions in over half the individuals. The phylogroup membership of an individual's numerically dominant strain explained some of the variation in the extent to which strains within an individual were heterogeneously distributed, with most heterogeneity observed when the numerically dominant strain belonged to phylogroups E or F, and the least when the dominant strain belonged to phylogroup B2. The results of this study support previous studies on pigs that demonstrated faecal sampling underestimates the genotype diversity present within a host. PMID:26034010

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

    PubMed Central

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

    1993-01-01

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

  1. Characterization of the YdeO Regulon in Escherichia coli

    PubMed Central

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

    2014-01-01

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

  2. Survival of Escherichia coli and Salmonella spp. in estuarine environments.

    PubMed

    Rhodes, M W; Kator, H

    1988-12-01

    Survival of Escherichia coli and Salmonella spp. in estuarine waters was compared over a variety of seasonal temperatures during in situ exposure in diffusion chambers. Sublethal stress was measured by both selective-versus-resuscitative enumeration procedures and an electrochemical detection method. E. coli and Salmonella spp. test suspensions, prepared to minimize sublethal injury, were exposed in a shallow tidal creek and at a site 7.1 km further downriver. Bacterial die-off and sublethal stress in filtered estuarine water were inversely related to water temperature. Salmonella spp. populations exhibited significantly less die-off and stress than did E. coli at water temperatures of less than 10 degrees C. Although the most pronounced reductions (ca. 3 log units) in test bacteria occurred during seasonally warm temperatures in the presence of the autochthonous microbiota, 10(2) to 10(4) test cells per ml remained after 2 weeks of exposure to temperatures of greater than 15 degrees C. Reductions in test bacteria were associated with increases in the densities of microflagellates and plaque-forming microorganisms. These studies demonstrated the survival potential of enteric bacteria in estuarine waters and showed that survival was a function of interacting biological and physical factors. PMID:3066291

  3. Rapid Method for Escherichia coli in the Cuyahoga River

    USGS Publications Warehouse

    Brady, Amie M.G.

    2007-01-01

    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.

  4. Regulation of neutrophil phagocytosis of Escherichia coli by antipsychotic drugs.

    PubMed

    Chen, Mao-Liang; Wu, Semon; Tsai, Tzung-Chieh; Wang, Lu-Kai; Tsai, Fu-Ming

    2014-12-01

    Antipsychotic drugs (APDs) have been used to ease the symptoms of schizophrenia. APDs have recently been reported to regulate the immune response. Our previous studies revealed that the atypical APDs risperidone and clozapine and the typical APD haloperidol can inhibit the phagocytic ability of macrophages. Our research next determined the effects of APDs on the phagocytic ability of neutrophils, which are the most abundant type of white blood cells in mammals. Here we provide evidence that clozapine and haloperidol can induce increased phagocytic uptake of Escherichia coli by differentiated HL-60 cells and by purified human neutrophils. Furthermore, clozapine and haloperidol can increase the myeloperoxidase activity and IL-8 production in neutrophils. Our results also show that clozapine can inhibit E. coli survival within differentiated HL-60 cells. Furthermore, clozapine and haloperidol are shown to enhance cell surface Mac-1 expression and the activated AKT signaling pathway in purified neutrophils exposed to E. coli. These results indicate that clozapine and haloperidol can increase the phagocytic ability of neutrophils by increasing AKT activation when cells are exposed to bacteria. PMID:25448498

  5. Nascentome Analysis Uncovers Futile Protein Synthesis in Escherichia coli

    PubMed Central

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

    2011-01-01

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

  6. Microaerobic Conversion of Glycerol to Ethanol in Escherichia coli

    PubMed Central

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

    2014-01-01

    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

  7. The binary protein-protein interaction landscape of Escherichia coli.

    PubMed

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

    2014-03-01

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

  8. Engineering Escherichia coli for canthaxanthin and astaxanthin biosynthesis.

    PubMed

    Cheng, Qiong; Tao, Luan

    2012-01-01

    Escherichia coli is a non-carotenogenic bacterium that could synthesize farnesyl pyrophosphate precursor through the isoprenoid pathway. Carotenoid production in E. coli requires heterologous expression of carotenoid synthesis genes. The carotenoid synthesis operons are assembled from genes isolated from carotenogenic bacterial sources. Expression of the different operons yields different carotenoid titers. The operons containing the idi gene give more than fivefold higher carotenoid titers than the operons lacking the idi gene. The carotenoid modification genes encoding ketolases and hydroxylases are incorporated into the operons for canthaxanthin and astaxanthin production. The ketolases and hydroxylases from different bacterial sources produce astaxanthin of different purity relative to the total carotenoids. Expression of the ketolases and hydroxylases closer to the promoter appears to give higher astaxanthin purity than expression farther from the promoter at the end of the operons. Balanced expression of ketolases and hydroxylases is critical to achieve high astaxanthin purity. Here, we describe methods to assemble carotenoid biosynthesis operons from carotenogenic gene clusters isolated from different bacterial sources and evaluate canthaxanthin or astaxanthin production in E. coli. PMID:22623300

  9. Asymptomatic bacteriuria Escherichia coli strains: adhesins, growth and competition.

    PubMed

    Roos, Viktoria; Nielsen, Eva M; Klemm, Per

    2006-09-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast to uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete against the UPEC strain CFT073 was also studied. The different ABU strains displayed a wide variety of the measured characteristics. Half of the ABU strains displayed functional type 1 fimbriae while only one expressed functional P fimbriae. A good correlation between the growth rate of a particular strain and the survival of the strain in competition against CFT073 was observed. Our results support the notion that for strains with reduced capacity to express fimbriae, the ability to grow fast in human urine becomes crucial for colonization of the urinary tract. PMID:16907735

  10. Biofilm and fluoroquinolone resistance of canine Escherichia coli uropathogenic isolates

    PubMed Central

    2014-01-01

    Background Escherichia coli is the most common uropathogen involved in urinary tract infection (UTI). Virulence of strains may differ, and may be enhanced by antimicrobial resistance and biofilm formation, resulting in increased morbidity and recurrent infections. The aim of this study was to evaluate the in vitro biofilm forming capacity of E. coli isolates from dogs with UTI, by using fluorescent in situ hybridization, and its association with virulence genes and antimicrobial resistance. Findings The proportion of biofilm-producing isolates significantly increased with the length of incubation time (P??0.05), but was significantly associated with afa, aer and the ?-lactamase genes (P?coli isolates from dogs with UTI. Biofilm formation may contribute to UTI treatment failure in dogs, through the development of bacterial reservoirs inside bladder cells, allowing them to overcome host immune defenses and to establish recurrent infections. PMID:25099929

  11. Functional heterogeneity of type 1 fimbriae of Escherichia coli.

    PubMed Central

    Sokurenko, E V; Courtney, H S; Abraham, S N; Klemm, P; Hasty, D L

    1992-01-01

    Escherichia coli and other members of the family Enterobacteriaceae express surface fibrillar structures, fimbriae, that promote bacterial adhesion to host receptors. Type 1 fimbriae possess a lectinlike component, FimH, that is commonly thought to cause binding to mannose-containing oligosaccharides of host receptors. Since adhesion of type 1 fimbriated organisms are inhibited by mannose, the reactions are described as mannose sensitive (MS). We have studied the adhesion of the type 1 fimbriated CSH-50 strain of E. coli (which expresses only type 1 fimbriae) to fibronectin (FN). E. coli CSH-50 does not bind detectable amounts of soluble FN but adheres well to immobilized plasma or cellular FN. This adhesion was inhibited by mannose-containing saccharides. By using purified domains of FN, it was found that E. coli CSH-50 adheres primarily to the amino-terminal and gelatin-binding domains, only one of which is glycosylated, in an MS fashion. Binding of the mannose-specific lectin concanavalin A to FN and ovalbumin was eliminated or reduced, respectively, by incubation with periodate or endoglycosidase. Adhesion of E. coli CSH-50 to ovalbumin was reduced by these treatments, but adhesion to FN was unaffected. E. coli CSH-50 also adheres to a synthetic peptide copying a portion of the amino-terminal FN domain (FNsp1) in an MS fashion. Purified CSH-50 fimbriae bound to immobilized FN and FNsp1 in an MS fashion and inhibited adhesion of intact organisms. However, fimbriae purified from HB101 (pPKL4), a recombinant strain harboring the entire type 1 fim gene locus and expressing functional type 1 fimbriae, neither bound to FN or FNsp1 nor inhibited E. coli adhesion to immobilized FN or FNsp1. These novel findings suggest that there are two forms of type 1 MS fimbriae. One form exhibits only the well-known MS lectinlike activity that requires a substratum of mannose-containing glycoproteins. The other form exhibits not only the MS lectinlike activity but also binds to nonglycosylated regions of proteins in an MS manner. Images PMID:1356930

  12. 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 ...

  13. 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.

  14. Specific Electromagnetic Effects of Microwave Radiation on Escherichia coli?

    PubMed Central

    Shamis, Yury; Taube, Alex; Mitik-Dineva, Natasa; Croft, Rodney; Crawford, Russell J.; Ivanova, Elena P.

    2011-01-01

    The present study investigated the effects of microwave (MW) radiation applied under a sublethal temperature on Escherichia coli. The experiments were conducted at a frequency of 18 GHz and at a temperature below 40°C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m3, and the electric field was determined to be 300 V/m. Both values were theoretically confirmed using CST Microwave Studio 3D Electromagnetic Simulation Software. As a negative control, E. coli cells were also thermally heated to temperatures up to 40°C using Peltier plate heating. Scanning electron microscopy (SEM) analysis performed immediately after MW exposure revealed that the E. coli cells exhibited a cell morphology significantly different from that of the negative controls. This MW effect, however, appeared to be temporary, as following a further 10-min elapsed period, the cell morphology appeared to revert to a state that was identical to that of the untreated controls. Confocal laser scanning microscopy (CLSM) revealed that fluorescein isothiocyanate (FITC)-conjugated dextran (150 kDa) was taken up by the MW-treated cells, suggesting that pores had formed within the cell membrane. Cell viability experiments revealed that the MW treatment was not bactericidal, since 88% of the cells were recovered after radiation. It is proposed that one of the effects of exposing E. coli cells to MW radiation under sublethal temperature conditions is that the cell surface undergoes a modification that is electrokinetic in nature, resulting in a reversible MW-induced poration of the cell membrane. PMID:21378041

  15. Isobutyraldehyde production from Escherichia coli by removing aldehyde reductase activity

    PubMed Central

    2012-01-01

    Background Increasing global demand and reliance on petroleum-derived chemicals will necessitate alternative sources for chemical feedstocks. Currently, 99% of chemical feedstocks are derived from petroleum and natural gas. Renewable methods for producing important chemical feedstocks largely remain unaddressed. Synthetic biology enables the renewable production of various chemicals from microorganisms by constructing unique metabolic pathways. Here, we engineer Escherichia coli for the production of isobutyraldehyde, which can be readily converted to various hydrocarbons currently derived from petroleum such as isobutyric acid, acetal, oxime and imine using existing chemical catalysis. Isobutyraldehyde can be readily stripped from cultures during production, which reduces toxic effects of isobutyraldehyde. Results We adopted the isobutanol pathway previously constructed in E. coli, neglecting the last step in the pathway where isobutyraldehyde is converted to isobutanol. However, this strain still overwhelmingly produced isobutanol (1.5?g/L/OD600 (isobutanol) vs 0.14?g/L/OD600 (isobutyraldehyde)). Next, we deleted yqhD which encodes a broad-substrate range aldehyde reductase known to be active toward isobutyraldehyde. This strain produced isobutanol and isobutyraldehyde at a near 1:1 ratio, indicating further native isobutyraldehyde reductase (IBR) activity in E. coli. To further eliminate isobutanol formation, we set out to identify and remove the remaining IBRs from the E. coli genome. We identified 7 annotated genes coding for IBRs that could be active toward isobutyraldehyde: adhP, eutG, yiaY, yjgB, betA, fucO, eutE. Individual deletions of the genes yielded only marginal improvements. Therefore, we sequentially deleted all seven of the genes and assessed production. The combined deletions greatly increased isobutyraldehyde production (1.5?g/L/OD600) and decreased isobutanol production (0.4?g/L/OD600). By assessing production by overexpression of each candidate IBR, we reveal that AdhP, EutG, YjgB, and FucO are active toward isobutyraldehyde. Finally, we assessed long-term isobutyraldehyde production of our best strain containing a total of 15 gene deletions using a gas stripping system with in situ product removal, resulting in a final titer of 35?g/L after 5?days. Conclusions In this work, we optimized E. coli for the production of the important chemical feedstock isobutyraldehyde by the removal of IBRs. Long-term production yielded industrially relevant titers of isobutyraldehyde with in situ product removal. The mutational load imparted on E. coli in this work demonstrates the versatility of metabolic engineering for strain improvements. PMID:22731523

  16. Phenotypic bistability in Escherichia coli's central carbon metabolism

    PubMed Central

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

    2014-01-01

    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

  17. Chromatographic Analysis of the Escherichia coli Polysialic Acid Capsule

    PubMed Central

    Steenbergen, Susan M.; Vimr, Eric R.

    2014-01-01

    Summary Polysialic acid capsules are the major virulence factors in Escherichia coli K1, K92, and groups B and C meningococci. The sialic acid monomers (2-keto-3-deoxy-5-acetamido-7,8,9-d-glycero-d-galacto-nonulosonic acids) comprising these homopolymeric polysaccharide chains can be selectively modified with 1,2-diamino-4,5-methylenedioxy-benzene to produce highly fluorescent quinoxalinone derivatives distinguished by their elution times during reverse phase chromatography. Here, we describe methods to release the constituent capsular polysialic acid monomers, detect, and quantify them by sensitive fluorometry. There are relatively few 2-keto acids in bacteria, making it possible to rapidly analyze samples even without prior purification of capsular polysaccharides. PMID:23299731

  18. Structure of the Cyclomodulin Cif from Pathogenic Escherichia coli

    SciTech Connect

    Hsu, Y.; Jubelin, G; Taieb, F; Nougayrède, J; Oswald, E; Stebbins, C

    2008-01-01

    Bacterial pathogens have evolved a sophisticated arsenal of virulence factors to modulate host cell biology. Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) use a type III protein secretion system (T3SS) to inject microbial proteins into host cells. The T3SS effector cycle inhibiting factor (Cif) produced by EPEC and EHEC is able to block host eukaryotic cell-cycle progression. We present here a crystal structure of Cif, revealing it to be a divergent member of the superfamily of enzymes including cysteine proteases and acetyltransferases that share a common catalytic triad. Mutation of these conserved active site residues abolishes the ability of Cif to block cell-cycle progression. Finally, we demonstrate that irreversible cysteine protease inhibitors do not abolish the Cif cytopathic effect, suggesting that another enzymatic activity may underlie the biological activity of this virulence factor.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  20. Enteropathogenic Escherichia coli diarrhea in hospitalized children in Bangladesh.

    PubMed Central

    Moyenuddin, M; Rahman, K M

    1985-01-01

    The role of enteropathogenic Escherichia coli (EPEC) was evaluated in a group of children with endemic diarrhea admitted to Dhaka Shishu Hospital in Dacca, Bangladesh. EPEC was detected in fecal samples of 23% of 104 cases and 8% of 74 concurrent control children. The most commonly isolated EPEC strains were serogroups O20a, O20c:K61; O20a, O20b:K84; O26:K60; and O18a, O18c:K77. Except for O26:K60, these groups had not been reported from Bangladesh. On testing for enterotoxin production, only two strains (serogroups O26:K60, O18a, and O18c:K77) were enterotoxigenic. None was enteroinvasive as tested in the guinea pig conjunctivitis model. Our study supports the concept that EPEC may be an important cause of endemic diarrhea in Bangladesh. PMID:3902881

  1. A Case of a Shiga Toxin Producing Escherichia Coli

    PubMed Central

    Cho, Seung-Hak; Kim, Jung-Beom; Park, Yong-Bae; Park, Mi-Sun; Chae, Hiun Suk

    2011-01-01

    We encountered a patient with hemolytic uremic syndrome (HUS) with persistent isolation of shiga toxin-producing Escherichia coli (STEC) for 3 weeks despite of having no clinical symptoms. STEC has been recognized as an important food-borne pathogen that causes severe diseases such as HUS. We characterized this STEC strain via a polymerase chain reaction, reverse-passive latex agglutination and the slide agglutination method. In this STEC strain, stx2 (shiga toxin), eaeA, tir, iha (adherence genes), espADB (type III secretion genes), and hlyA, ehxA, clyA (hemolysin genes) were present. The O antigen of the strain was non-typable. PMID:22028174

  2. Engineering Escherichia coli for fumaric acid production from glycerol.

    PubMed

    Li, Ning; Zhang, Bo; Wang, Zhiwen; Tang, Ya-Jie; Chen, Tao; Zhao, Xueming

    2014-12-01

    The evolved mutant Escherichia coli E2 previously developed for succinate production from glycerol was engineered in this study for fumaric acid production under aerobic conditions. Through deletion of three fumarases, 3.65g/L fumaric acid was produced with the yield of 0.25mol/mol glycerol and a large amount of acetate was accumulated as the main byproduct. In order to reduce acetate production several strategies were attempted, among which increasing the flux of the anaplerotic pathways through overexpression of phosphoenolpyruvate carboxylase gene ppc or the glyoxylate shunt operon aceBA effectively reduced acetate and improved fumaric acid production. In fed-batch culture, the resulting strain EF02(pSCppc) produced 41.5g/L fumaric acid from glycerol with 70% of the maximum theoretical yield and an overall productivity of 0.51g/L/h. PMID:25463785

  3. Termination structures in the Escherichia coli chromosome replication fork trap.

    PubMed

    Duggin, Iain G; Bell, Stephen D

    2009-04-01

    The Escherichia coli chromosome contains two opposed sets of unidirectional DNA replication pause (Ter) sites that, according to the replication fork trap theory, control the termination of chromosome replication by restricting replication fork fusion to the terminus region. In contrast, a recent hypothesis suggested that termination occurs at the dif locus instead. Using two-dimensional agarose gel electrophoresis, we examined DNA replication intermediates at the Ter sites and at dif in wild-type cells. Two definitive signatures of site-specific termination--specific replication fork arrest and converging replication forks--were clearly detected at Ter sites, but not at dif. We also detected a significant pause during the latter stages of replication fork convergence at Ter sites. Quantification of fork pausing at the Ter sites in both their native chromosomal context and the plasmid context further supported the fork trap model. PMID:19233209

  4. Intramolecular dynamics of structure of alkaline phosphatase from Escherichia coli

    NASA Astrophysics Data System (ADS)

    Mazhul, Vladimir M.; Mjakinnik, Igor V.; Volkova, Alena N.

    1995-01-01

    The luminescent analysis with nano- and millisecond time resolution of intramolecular dynamics of Escherichia coli alkaline phosphatase was carried out. The effect of pH within the range 7.2 - 9.0, thermal inactivation, limited proteolysis by trypsin, binding of pyrophosphate, interconversion of enzyme and apoenzyme, the replacement of Zn2+ and Mg2+ in the active site by Cd2+ and Ni2+ on the spectral and kinetic parameters of luminescence was investigated. The essential changes of the level of nano- and millisecond dynamics of protein structure were found to correlate with the shift of enzymatic activity. The importance of small- and large-scale flexibility of protein structure for the act of enzymatic catalysis realization was shown.

  5. Detergent (sodium dodecyl sulfate) shock proteins in Escherichia coli

    SciTech Connect

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

    1991-01-01

    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.

  6. Engineering Escherichia coli to synthesize free fatty acids

    PubMed Central

    Lennen, Rebecca M.; Pfleger, Brian F.

    2013-01-01

    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

  7. Phenotypic bistability in Escherichia coli's central carbon metabolism.

    PubMed

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

    2014-01-01

    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

  8. Production of human tetraspanin proteins in Escherichia coli.

    PubMed

    Tarry, Michael; Skaar, Karin; Heijne, Gunnar von; Draheim, Roger R; Högbom, Martin

    2012-04-01

    Tetraspanins are found in multicellular eukaryotes and are generally thought to act as scaffolding proteins, localizing multiple proteins to a specific region of the cell membrane. Activities for tetraspanins have been identified in several fundamental processes such as motility, cell adhesion, proliferation and viral entry. Tetraspanins are also key players in cancer development and progression. However, structural and biochemical information on tetraspanins is decidely limited, due in no small part to the difficulties associated with expressing eukaryotic membrane proteins. In this study, we have used GFP fusions of a library of human tetraspanin proteins to identify growth conditions for expression in Escherichia coli. Three tetraspanin-GFP proteins could be produced at high enough levels to allow subsequent purification, paving the way for future structural and biochemical studies. PMID:22381464

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

    PubMed Central

    Baquero, Fernando; Tobes, Raquel

    2013-01-01

    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

  10. Mutator specificity of Escherichia coli alkB117 allele.

    PubMed

    Nieminuszczy, Jadwiga; Janion, Celina; Grzesiuk, Elzbieta

    2006-01-01

    The Escherichia coli AlkB protein encoded by alkB gene was recently found to repair cytotoxic DNA lesions 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) by using a novel iron-catalysed oxidative demethylation mechanism that protects the cell from the toxic effects of methylating agents. Mutation in alkB results in increased sensitivity to MMS and elevated level of MMS-induced mutations. The aim of this study was to analyse the mutational specificity of alkB117 in a system developed by J.H. Miller involving two sets of E. coli lacZ mutants, CC101-106 allowing the identification of base pair substitutions, and CC107-CC111 indicating frameshift mutations. Of the six possible base substitutions, the presence of alkB117 allele led to an increased level of GC-->AT transitions and GC-->TA and AT-->TA transversions. After MMS treatment the level of GC-->AT transitions increased the most, 22-fold. Among frameshift mutations, the most numerous were -2CG, -1G, and -1A deletions and +1G insertion. MMS treatment appreciably increased all of the above types of frameshifts, with additional appearance of the +1A insertion. PMID:16733554

  11. Understanding carbon catabolite repression in Escherichia coli using quantitative models.

    PubMed

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

    2015-02-01

    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

  12. Association between Antimicrobial Consumption and Resistance in Escherichia coli?

    PubMed Central

    Bergman, Miika; Nyberg, Solja T.; Huovinen, Pentti; Paakkari, Pirkko; Hakanen, Antti J.

    2009-01-01

    During a 9-year study period from 1997 through 2005, the association between antimicrobial resistance rates in Escherichia coli and outpatient antimicrobial consumption was investigated in 20 hospital districts in Finland. A total of 754,293 E. coli isolates, mainly from urine samples, were tested for antimicrobial resistance in 26 clinical microbiology laboratories. The following antimicrobials were studied: ampicillin, amoxicillin-clavulanate, cephalosporins, fluoroquinolones, trimethoprim, trimethoprim-sulfamethoxazole, pivmecillinam, and nitrofurantoin. We applied a protocol used in earlier studies in which the level of antimicrobial consumption over 1 year was compared with the level of resistance in the next year. Statistically significant associations were found for nitrofurantoin use versus nitrofurantoin resistance (P < 0.0001), cephalosporin use versus nitrofurantoin resistance (P = 0.0293), amoxicillin use versus fluoroquinolone resistance (P = 0.0031), and fluoroquinolone use versus ampicillin resistance (P = 0.0046). Interestingly, we found only a few associations between resistance and antimicrobial consumption. The majority of the associations studied were not significant, including the association between fluoroquinolone use and fluoroquinolone resistance. PMID:19104012

  13. Temperature-sensitive autolysis-defective mutants of Escherichia coli.

    PubMed Central

    Harkness, R E; Ishiguro, E E

    1983-01-01

    Two independently isolated temperature-sensitive autolysis-defective mutants of Escherichia coli LD5 (thi lysA dapD) were characterized. The mutants were isolated by screening the survivors of a three-step enrichment process involving sequential treatments with bactericidal concentrations of D-cycloserine, benzyl-penicillin, and D-cycloserine at 42 degrees C. Cultures of the mutants underwent autolysis during beta-lactam treatment, D-cycloserine treatment, or diaminopimelic acid deprivation at 30 degrees C. The same treatments at 42 degrees C inhibited growth but did not induce lysis of the mutants. The minimum inhibitory concentrations of selected beta-lactam antibiotics and D-cycloserine were identical for the parent and mutant strains at both 30 and 42 degrees C. Both mutants failed to form colonies at 42 degrees C, and both gave rise to spontaneous temperature-resistant revertants. The revertants exhibited the normal lytic response when treated with D-cycloserine and beta-lactams or when deprived of diaminopimelic acid at 42 degrees C. The basis for the autolysis-defective phenotype of these mutants could not be determined. However, a nonspecific in vitro assay for peptidoglycan hydrolase activity in cell-free extracts indicated that both mutants were deficient in a peptidoglycan hydrolase. Both mutations were localized to the 56- to 61-min region of the E. coli chromosome by F' complementation. PMID:6134714

  14. Escherichia coli ribonucleotide reductase expression is cell cycle regulated.

    PubMed Central

    Sun, L; Fuchs, J A

    1992-01-01

    The expression of the genes encoding ribonucleotide reductase in Escherichia coli was investigated in cultures synchronized by obtaining the smallest cells in a population after sucrose gradient centrifugation. Specific activity of ribonucleotide reductase and DNA initiation were found to increase in parallel, periodically as a function of the cell cycle. The expression of nrd was also determined in cells synchronized by periodic repeated doubling in a phosphate limited medium. Antibodies directed against the B2 subunit of ribonucleotide reductase were raised in a rabbit and purified. Immunoprecipitation of the B2 subunit and RNA-DNA dot blot hybridization assays were developed and employed to determine the expression of ribonucleotide reductase translational and transcriptional products during the cell cycle. Both of nrd-mRNA and B2 subunit expression were found to increase each generation at approximately the same time DNA synthesis was initiated and then to decrease back to the basal level shortly after DNA initiation. These results provided evidence of cell cycle dependent regulation of ribonucleotide reductase in E. coli. When the upstream regulatory region of nrd was fused to a promoterless lacZ gene on a single copy plasmid, lac-mRNA and beta-galactosidase were found to be synthesized in parallel to nrd expression from the chromosomal operon. When nrd sequences surrounding the promoter were removed from this construct, lac-mRNA and beta-galactosidase synthesis were no longer cell cycle regulated. Images PMID:1384814

  15. Epidemiology and Clinical Manifestations of Enteroaggregative Escherichia coli

    PubMed Central

    Hebbelstrup Jensen, Betina; Olsen, Katharina E. P.; Struve, Carsten; Petersen, Andreas Munk

    2014-01-01

    SUMMARY Enteroaggregative Escherichia coli (EAEC) represents a heterogeneous group of E. coli strains. The pathogenicity and clinical relevance of these bacteria are still controversial. In this review, we describe the clinical significance of EAEC regarding patterns of infection in humans, transmission, reservoirs, and symptoms. Manifestations associated with EAEC infection include watery diarrhea, mucoid diarrhea, low-grade fever, nausea, tenesmus, and borborygmi. In early studies, EAEC was considered to be an opportunistic pathogen associated with diarrhea in HIV patients and in malnourished children in developing countries. In recent studies, associations with traveler's diarrhea, the occurrence of diarrhea cases in industrialized countries, and outbreaks of diarrhea in Europe and Asia have been reported. In the spring of 2011, a large outbreak of hemolytic-uremic syndrome (HUS) and hemorrhagic colitis occurred in Germany due to an EAEC O104:H4 strain, causing 54 deaths and 855 cases of HUS. This strain produces the potent Shiga toxin along with the aggregative fimbriae. An outbreak of urinary tract infection associated with EAEC in Copenhagen, Denmark, occurred in 1991; this involved extensive production of biofilm, an important characteristic of the pathogenicity of EAEC. However, the heterogeneity of EAEC continues to complicate diagnostics and also our understanding of pathogenicity. PMID:24982324

  16. Enhanced Deletion Formation by Aberrant DNA Replication in Escherichia Coli

    PubMed Central

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

    1997-01-01

    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

  17. Porin activity in the osmotic shock fluid of Escherichia coli.

    PubMed Central

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

    1978-01-01

    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

  18. Wobble decoding by the Escherichia coli selenocysteine insertion machinery

    PubMed Central

    Xu, Jianqiang; Croitoru, Victor; Rutishauser, Dorothea; Cheng, Qing; Arnér, Elias S.J.

    2013-01-01

    Selenoprotein expression in Escherichia coli redefines specific single UGA codons from translational termination to selenocysteine (Sec) insertion. This process requires the presence of a Sec Insertion Sequence (SECIS) in the mRNA, which forms a secondary structure that binds a unique Sec-specific elongation factor that catalyzes Sec insertion at the predefined UGA instead of release factor 2-mediated termination. During overproduction of recombinant selenoproteins, this process nonetheless typically results in expression of UGA-truncated products together with the production of recombinant selenoproteins. Here, we found that premature termination can be fully avoided through a SECIS-dependent Sec-mediated suppression of UGG, thereby yielding either tryptophan or Sec insertion without detectable premature truncation. The yield of recombinant selenoprotein produced with this method approached that obtained with a classical UGA codon for Sec insertion. Sec-mediated suppression of UGG thus provides a novel method for selenoprotein production, as here demonstrated with rat thioredoxin reductase. The results also reveal that the E. coli selenoprotein synthesis machinery has the inherent capability to promote wobble decoding. PMID:23982514

  19. Analysis of Heme Biosynthetic Pathways in a Recombinant Escherichia coli.

    PubMed

    Pranawidjaja, Stephanie; Choi, Su-In; Lay, Bibiana W; Kim, Pil

    2015-06-28

    Bacterial heme was produced from a genetic-engineered Escherichia coli via the porphyrin pathway and it was useful as an iron resource for animal feed. The amount of the E. colisynthesized heme, however, was only few milligrams in a culture broth and it was not enough for industrial applications. To analyze heme biosynthetic pathways, an engineered E. coli artificially overexpressing ALA synthase (hemA from Rhodobacter sphaeroides) and pantothenate kinase (coaA gene from self geneome) was constructed as a bacterial heme-producing strain, and both the transcription levels of pathway genes and the intermediates concentrations were determined from batch and continuous cultures. Transcription levels of the pathway genes were not significantly changed among the tested conditions. Intracellular intermediate concentrations indicated that aminolevulinic acid (ALA) and coenzyme A (CoA) were enhanced by the hemA-coaA co-expression. Intracellular coproporphyrinogen I and protoporphyrin IX accumulation suggested that the bottleneck steps in the heme biosynthetic pathway could be the spontaneous conversion of HMB to coproporphyrinogen I and the limited conversion of protoporphyrin IX to heme, respectively. A strategy to increase the conversion of ALA to heme is discussed based on the results. PMID:25537720

  20. Capture efficiency of Escherichia coli in fimbriae-mediated immunoimmobilization

    PubMed Central

    Suo, Zhiyong; Yang, Xinghong; Deliorman, Muhammedin; Cao, Ling; Avci, Recep

    2012-01-01

    Capturing pathogens on a sensor surface is one of the most important steps in the design of a biosensor. The efficiency of a biosensor at capturing pathogens has direct bearing on its sensitivity. In this work we investigated the capturing of Escherichia coli on substrates modified with antibodies targeting different types of fimbriae: K88ab (F4), K88ac (F4), K99 (F5), 987P (F6), F41 and CFA/I. The results suggest that all these fimbriae can be used for the efficient immobilization of living E. coli cells. The immobilization efficiency was affected by the purity and clone type of the antibody and the fimbriae expression level of the bacteria. For a specific fimbriae type, a higher immobilization efficiency was often observed with the monoclonal antibodies. Immunoimmobilization was utilized in an antibody microarray immersed in a mixed culture of pathogens to demonstrate the rapid and simultaneous label-free detection of multiple pathogens within less than an hour using a single test. The capture rate of living pathogens exceeds a single bacterium per 100×100 ?m2 area per half an hour of incubation for a bulk concentration of 105 cfu/ml. PMID:22149536

  1. Analysis of bottled water for Escherichia coli and total coliforms.

    PubMed

    Grant, M A

    1998-03-01

    U.S. Food and Drug Administration regulations governing bottled water include microbiological quality guidelines based on coliform counts. Recently, a new MF medium for simultaneous detection of total coliforms and Escherichia coli was developed. This medium, m-ColiBlue24 (m-CB) was compared to m-Endo medium and an International Organization for Standardization standard coliform medium, lactose agar with Tergitol 7. Coliform analysis was conducted on 104 brands of bottled water from 10 countries. Some samples were additionally analyzed for heterotrophic plate count on Pseudomonas sp. populations, including P. aeruginosa. Presumptive coliform colonies were found in 5.8% of the samples with m-CB, 1.9% with m-Endo and 11.5% with lactose agar with Tergitol 7. None of the presumptive coliforms from any of the three media were verified as true coliforms in subsequent analysis. Consequently, the presumptive recovery rates actually represented false-positive error (FPE) rates. The FPE for m-CB and m-Endo were not statistically different (P < 0.05) but the FPE for lactose agar with Tergitol 7 was significantly larger. PMID:9708306

  2. Molecular response of Escherichia coli adhering onto nanoscale topography

    NASA Astrophysics Data System (ADS)

    Rizzello, Loris; Galeone, Antonio; Vecchio, Giuseppe; Brunetti, Virgilio; Sabella, Stefania; Pompa, Pier Paolo

    2012-10-01

    Bacterial adhesion onto abiotic surfaces is an important issue in biology and medicine since understanding the bases of such interaction represents a crucial aspect in the design of safe implant devices with intrinsic antibacterial characteristics. In this framework, we investigated the effects of nanostructured metal substrates on Escherichia coli adhesion and adaptation in order to understand the bio-molecular dynamics ruling the interactions at the interface. In particular, we show how highly controlled nanostructured gold substrates impact the bacterial behavior in terms of morphological changes and lead to modifications in the expression profile of several genes, which are crucially involved in the stress response and fimbrial synthesis. These results mainly demonstrate that E. coli cells are able to sense even slight changes in surface nanotopography and to actively respond by activating stress-related pathways. At the same time, our findings highlight the possibility of designing nanoengineered substrates able to trigger specific bio-molecular effects, thus opening the perspective of smartly tuning bacterial behavior by biomaterial design.

  3. Microbial Synthesis of Myrcene by Metabolically Engineered Escherichia coli.

    PubMed

    Kim, Eun-Mi; Eom, Jin-Hee; Um, Youngsoon; Kim, Yunje; Woo, Han Min

    2015-05-13

    Myrcene, a monoterpene (C10), has gathered attention as a starting material for high-value compounds, such as geraniol/linalool and (-)-menthol. Metabolic engineering has been successfully applied to produce monoterpenes, such as pinene and limonene, at high levels in microbial hosts. However, microbial synthesis of myrcene has not yet been reported. Thus, we metabolically engineered Escherichia coli for production of myrcene by introducing a heterologous mevalonate pathway and overexpressing tailoring enzymes, such as geranyl diphosphate synthase (GPPS) and myrcene synthase (MS). Although MSs have broad ranges of functionality for producing various monoterpenes, our engineered E. coli strains harboring MS from Quercus ilex L. produced only myrcene (1.67 ± 0.029 mg/L). Subsequent engineering resulted in higher production of myrcene by optimizing the levels of GPPS in amino-acid-enriched (EZ-rich) defined medium, where glycerol as a carbon source was used. The production level of myrcene (58.19 ± 12.13 mg/L) was enhanced by 34-fold using in situ two-phase extraction to eliminate cellular toxicity and the evaporation of myrcene. PMID:25909988

  4. Bacteriophages with the ability to degrade uropathogenic Escherichia coli biofilms.

    PubMed

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

    2012-04-01

    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

  5. In vivo immobilization of D-hydantoinase in Escherichia coli.

    PubMed

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

    2014-07-01

    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

  6. Dissecting Escherichia coli Outer Membrane Biogenesis Using Differential Proteomics

    PubMed Central

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

    2014-01-01

    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

  7. Composite analysis for Escherichia coli at coastal beaches

    USGS Publications Warehouse

    Bertke, E.E.

    2007-01-01

    At some coastal beaches, concentrations of fecal-indicator bacteria can differ substantially between multiple points at the same beach at the same time. Because of this spatial variability, the recreational water quality at beaches is sometimes determined by stratifying a beach into several areas and collecting a sample from each area to analyze for the concentration of fecal-indicator bacteria. The average concentration of bacteria from those points is often used to compare to the recreational standard for advisory postings. Alternatively, if funds are limited, a single sample is collected to represent the beach. Compositing the samples collected from each section of the beach may yield equally accurate data as averaging concentrations from multiple points, at a reduced cost. In the study described herein, water samples were collected at multiple points from three Lake Erie beaches and analyzed for Escherichia coli on modified mTEC agar (EPA Method 1603). From the multiple-point samples, a composite sample (n = 116) was formed at each beach by combining equal aliquots of well-mixed water from each point. Results from this study indicate that E. coli concentrations from the arithmetic average of multiple-point samples and from composited samples are not significantly different (t = 1.59, p = 0.1139) and yield similar measures of recreational water quality; additionally, composite samples could result in a significant cost savings.

  8. Gene transcription and chromosome replication in Escherichia coli.

    PubMed

    Zhou, P; Bogan, J A; Welch, K; Pickett, S R; Wang, H J; Zaritsky, A; Helmstetter, C E

    1997-01-01

    Transcript levels of several Escherichia coli genes involved in chromosome replication and cell division were measured in dnaC2(Ts) mutants synchronized for chromosome replication by temperature shifts. Levels of transcripts from four of the genes, dam, nrdA, mukB, and seqA, were reduced at a certain stage during chromosome replication. The magnitudes of the decreases were similar to those reported previously ftsQ and ftsZ (P. Zhou and C. E. Helmstetter, J. Bacteriol. 176:6100-6106, 1994) but considerably less than those seen with dnaA, gidA, and mioC (P. W. Theisen, J. E. Grimwade, A. C. Leonard, J. A. Bogan, and C. E. Helmstetter, Mol. Microbiol. 10:575-584, 1993). The decreases in transcripts appeared to correlate with the estimated time at which the genes replicated. This same conclusion was reached in studies with synchronous cultures obtained with the baby machine in those instances in which periodicities in transcript levels were clearly evident. The transcriptional levels for two genes, minE and tus, did not fluctuate significantly, whereas the transcripts for one gene, iciA, appeared to increase transiently. The results support the idea that cell cycle timing in E. coli is not governed by timed bursts of gene expression, since the overall findings summarized in this report are generally consistent with cell cycle-dependent transient inhibitions of transcription rather than stimulations. PMID:8981994

  9. Photoreactivation of Escherichia coli is impaired at high growth temperatures.

    PubMed

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

    2015-06-01

    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

  10. Metabolic engineering of itaconate production in Escherichia coli.

    PubMed

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

    2015-01-01

    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

  11. Ultraviolet-Sensitive Mutator Strain of Escherichia coli K-12

    PubMed Central

    Siegel, Eli C.

    1973-01-01

    An ultraviolet (UV)-sensitive mutator gene, mutU, was identified in Escherichia coli K-12. The mutation mutU4 is very close to uvrD, between metE and ilv, on the E. coli chromosome. It was recessive as a mutator and as a UV-sensitive mutation. The frequency of reversion of trpA46 on an F episome was increased by mutU4 on the chromosome. The mutator gene did not increase mutation frequencies in virulent phages or in lytically grown phage ?. The mutU4 mutation predominantly induced transitional base changes. Mutator strains were normal for recombination and host-cell reactivation of UV-irradiated phage T1. They were normally resistant to methyl methanesulfonate and were slightly more sensitive to gamma irradiation than Mut+ strains. UV irradiation induced mutations in a mutU4 strain, and phage ? was UV-inducible. Double mutants containing mutU4 and recA, B, or C were extremely sensitive to UV irradiation; a mutU4 uvrA6 double mutant was only slightly more sensitive than a uvrA6 strain. The mutU4 uvrA6 and mutU4 recA, B, or C double mutants had mutation rates similar to that of a mutU4 strain. Two UV-sensitive mutators, mut-9 and mut-10, isolated by Liberfarb and Bryson in E. coli B/UV, were found to be co-transducible with ilv in the same general region as mutU4. PMID:4345920

  12. Response of Escherichia coli growth rate to osmotic shock

    PubMed Central

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

    2014-01-01

    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

  13. Modifying thermostability of appA from Escherichia coli.

    PubMed

    Zhu, Weihua; Qiao, Dairong; Huang, Min; Yang, Ge; Xu, Hui; Cao, Yi

    2010-10-01

    In order to improve the thermostability of Escherichia coli AppA phytase, Error-prone PCR was used to randomize mutagenesis appA gene, and a gene mutation library was constructed. A mutant I408L was selected from the library by the method of high-throughput screening with 4-methyl-umbelliferylphosphate (4-MUP). The appA gene of the mutant was cloned and expressed in E. coli Origami (DE3). The recombinant protein was purified by Ni-affinity chromatography, and the enzymatic features were analyzed. The results indicated that AppA phytase activities of mutant I408L and wild-type (WT) strain remained at 51.3 and 28%, respectively, after treatment at 85°C for 5 min. It means that the thermostability enhancement of AppA phytase I408L was 23.3% more as compared with WT. The K (m) of both phytase were 0.18 and 0.25 mM, respectively, which indicated that the catalyzing efficiency of I408L was improved. AppA phytase of mutant I408L showed a significant enhancement against trypsin, which was nearly three times compared with WT. In addition, AppA phytase of mutant could be activated by Mg(2+) and Mn(2+); in contrast, it could be inhibited by Ca(2+), Co(2+), Cu(2+), and K(+) in varying degrees, and the enzymatic activity was almost lost the presence of Fe(3+) and Zn(2+). It appears that screening thermotolerant phytase of E. coli by high throughput screening with a fluorescence substrate is a fast, simple, and effective method. The mutant I408L obtained in this study could be used for the large-scale commercial production of phytase. PMID:20213104

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

    NASA Astrophysics Data System (ADS)

    Nieves, Ismael U.

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

  15. Escherichia coli is unable to produce pyrroloquinoline quinone (PQQ).

    PubMed

    Matsushita, K; Arents, J C; Bader, R; Yamada, M; Adachi, O; Postma, P W

    1997-10-01

    Many bacteria can synthesize the cofactor pyrroloquinoline quinone (PQQ), a cofactor of several dehydrogenases, including glucose dehydrogenase (GCD). Among the enteric bacteria, Klebsiella pneumoniae has been shown to contain the genes required for PQQ biosynthesis. Escherichia coli and Salmonella typhimurium were thought to be unable to synthesize PQQ but it has been reported that strain EF260, a derivative of E. coli FB8, can synthesize PQQ after mutation and can oxidize glucose to gluconate via the GCD/PQQ pathway (F. Biville, E. Turlin & F. Gasser, 1991, J Gen Microbiol 137, 1775-1782). We have re-investigated this claim and conclude that it is most likely erroneous. (i) Strain EF260, isolated originally by Biville and coworkers, was unable to synthesize a holo-enzyme GCD unless PQQ was supplied to the growth medium. No GCD activity could be detected in membrane fractions. (ii) The amount of PQQ detected in the growth medium of EF260 was very low and not very different from that found in a medium with its parent strain or in a medium containing no cells. (iii) EF260 cells were unable to produce gluconate from glucose via the PQQ/GCD pathway. (iv) Introduction of a gcd::Cm deletion in EF260, eliminating GCD, did not affect glucose metabolism. This suggested a pathway for glucose metabolism other than the PQQ/GCD pathway. (v) Glucose uptake and metabolism in EF260 involved a low-affinity transport system of unknown identity, followed most likely by phosphorylation via glucokinase. It is concluded that E. coli cannot synthesize PQQ and that it lacks genes required for PQQ biosynthesis. PMID:9353919

  16. High-yield anthocyanin biosynthesis in engineered Escherichia coli.

    PubMed

    Yan, Yajun; Li, Zhen; Koffas, Mattheos A G

    2008-05-01

    Anthocyanins are red, purple, or blue plant water-soluble pigments. In the past two decades, anthocyanins have received extensive studies for their anti-oxidative, anti-inflammatory, anti-cancer, anti-obesity, anti-diabetic, and cardioprotective properties. In the present study, anthocyanin biosynthetic enzymes from different plant species were characterized and employed for pathway construction leading from inexpensive precursors such as flavanones and flavan-3-ols to anthocyanins in Escherichia coli. The recombinant E. coli cells successfully achieved milligram level production of two anthocyanins, pelargonidin 3-O-glucoside (0.98 mg/L) and cyanidin 3-O-gluside (2.07 mg/L) from their respective flavanone precursors naringenin and eriodictyol. Cyanidin 3-O-glucoside was produced at even higher yields (16.1 mg/L) from its flavan-3-ol, (+)-catechin precursor. Further studies demonstrated that availability of the glucosyl donor, UDP-glucose, was the key metabolic limitation, while product instability at normal pH was also identified as a barrier for production improvement. Therefore, various optimization strategies were employed for enhancing the homogenous synthesis of UDP-glucose in the host cells while at the same time stabilizing the final anthocyanin product. Such optimizations included culture medium pH adjustment, the creation of fusion proteins and the rational manipulation of E. coli metabolic network for improving the intracellular UDP-glucose metabolic pool. As a result, production of pelargonidin 3-O-glucoside at 78.9 mg/L and cyanidin 3-O-glucoside at 70.7 mg/L was achieved from their precursor flavan-3-ols without supplementation with extracellular UDP-glucose. These results demonstrate the efficient production of the core anthocyanins for the first time and open the possibility for their commercialization for pharmaceutical and nutraceutical applications. PMID:18023053

  17. Engineered biosynthesis of an ansamycin polyketide precursor in Escherichia coli

    PubMed Central

    Watanabe, Kenji; Rude, Mathew A.; Walsh, Christopher T.; Khosla, Chaitan

    2003-01-01

    Ansamycins such as rifamycin, ansamitocin, and geldanamycin are an important class of polyketide natural products. Their biosynthetic pathways are especially complex because they involve the formation of 3-amino-5-hydroxybenzoic acid (AHBA) followed by backbone assembly by a hybrid nonribosomal peptide synthetase/polyketide synthase. We have reconstituted the ability to synthesize 2,6-dimethyl-3,5,7-trihydroxy-7-(3?-amino-5?-hydroxyphenyl)-2,4-heptadienoic acid (P8/1-OG), an intermediate in rifamycin biosynthesis, in an extensively manipulated strain of Escherichia coli. The parent strain, BAP1, contains the sfp phosphopantetheinyl transferase gene from Bacillus subtilis, which posttranslationally modifies polyketide synthase and nonribosomal peptide synthetase modules. AHBA biosynthesis in this host required introduction of seven genes from Amycolatopsis mediterranei, which produces rifamycin, and Actinosynnema pretiosum, which produces ansamitocin. Because the four-module RifA protein (530 kDa) from the rifamycin synthetase could not be efficiently produced in an intact form in E. coli, it was genetically split into two bimodular proteins separated by matched linker pairs to facilitate efficient inter-polypeptide transfer of a biosynthetic intermediate. A derivative of BAP1 was engineered that harbors the AHBA biosynthetic operon, the bicistronic RifA construct and the pccB and accA1 genes from Streptomyces coelicolor, which enable methylmalonyl-CoA biosynthesis. Fermentation of this strain of E. coli yielded P8/1-OG, an N-acetyl P8/1-OG analog, and AHBA. In addition to providing a fundamentally new route to shikimate and ansamycin-type compounds, this result enables further genetic manipulation of AHBA-derived polyketide natural products with unprecedented power. PMID:12888623

  18. Binding of collagens to an enterotoxigenic strain of Escherichia coli

    SciTech Connect

    Visai, L.; Speziale, P.; Bozzini, S. (Univ. of Pavia (Italy))

    1990-02-01

    An enterotoxigenic strain of Escherichia coli, B34289c, has been shown to bind the N-terminal region of fibronectin with high affinity. We now report that this strain also binds collagen. The binding of 125I-labeled type II collagen to bacteria was time dependent and reversible. Bacteria expressed a limited number of collagen receptors (2.2 x 10(4) per cell) and bound collagen with a Kd of 20 nM. All collagen types tested (I to V) as well as all tested cyanogen bromide-generated peptides (alpha 1(I)CB2, alpha 1(I)CB3, alpha 1(I)CB7, alpha 1(I)CB8, and alpha 2(I)CB4) were recognized by bacterial receptors, as demonstrated by the ability of these proteins to inhibit the binding of 125I-labeled collagen to bacteria. Of several unlabeled proteins tested in competition experiments, fibronectin and its N-terminal region strongly inhibited binding of the radiolabeled collagen to E. coli cells. Conversely, collagen competed with an 125I-labeled 28-kilodalton fibronectin fragment for bacterial binding. Collagen bound to bacteria could be displaced by excess amounts of either unlabeled fibronectin or its N-terminal fragment. Similarly, collagen could displace 125I-labeled N-terminal peptide of fibronectin bound to the bacterial cell surface. Bacteria grown at 41 degrees C or in the presence of glucose did not express collagen or fibronectin receptors. These results indicate the presence of specific binding sites for collagen on the surface of E. coli cells and furthermore that the collagen and fibronectin binding sites are located in close proximity, possibly on the same structure.

  19. Recombinational construction in Escherichia coli of infectious adenoviral?genomes

    PubMed Central

    Crouzet, Joël; Naudin, Laurent; Orsini, Cécile; Vigne, Emmanuelle; Ferrero, Lucy; Le Roux, Aude; Benoit, Patrick; Latta, Martine; Torrent, Christophe; Branellec, Didier; Denèfle, Patrice; Mayaux, Jean-François; Perricaudet, Michel; Yeh, Patrice

    1997-01-01

    A two-step gene replacement procedure was developed that generates infectious adenoviral genomes through homologous recombination in Escherichia coli. As a prerequisite, a human adenovirus serotype 5 (Ad5)-derived genome was first introduced as a PacI restriction fragment into an incP-derived replicon which, in contrast to ColE1-derivatives (e.g., pBR322 or pUC plasmids), is functional in a polA mutant of E. coli. Any modification can be introduced at will following two consecutive homologous recombinations between the incP/Ad5 replicon and the ColE1 plasmid. The overall procedure requires only the in vitro engineering of the ColE1-derivative by flanking the desired modification with small stretches of identical sequences. In the first step, a cointegrate between the tetracycline-resistant incP/Ad5 replicon and the kanamycin-resistant ColE1-derivative is selected by growing the polA host in the presence of both antibiotics. Resolution of this cointegrate is further selected in sucrose growth conditions due to the loss of a conditional suicide marker (the sacB gene of Bacillus subtilis) present in the ColE1 plasmid, leading to unmodified and modified incP/Ad5 replicons that can be differentiated upon restriction analysis. Consecutive rounds of this two-step cloning procedure allowed the introduction of multiple independent modifications within the virus genome, with no requirement for an intermediate virus. The potential of this procedure is demonstrated by the recovery of several E1E3E4-deleted adenoviruses following transfection of the corresponding E. coli-derived genomes in IGRP2 cells. PMID:9037067

  20. Improving Microbial Biogasoline Production in Escherichia coli Using Tolerance Engineering

    PubMed Central

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

    2014-01-01

    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

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

    PubMed

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

    2015-07-01

    Mounting environmental concerns associated with the use of petroleum-based chemical manufacturing practices has generated significant interest in the development of biological alternatives for the production of propionate. However, biological platforms for propionate production have been limited to strict anaerobes, such as Propionibacteria and select Clostridia. In this work, we demonstrated high-level heterologous production of propionate under microaerobic conditions in engineered Escherichia coli. Activation of the native Sleeping beauty mutase (Sbm) operon not only transformed E. coli to be propionogenic (i.e., propionate-producing) but also introduced an intracellular "flux competition" between the traditional C2-fermentative pathway and the novel C3-fermentative pathway. Dissimilation of the major carbon source of glycerol was identified to critically affect such "flux competition" and, therefore, propionate synthesis. As a result, the propionogenic E. coli was further engineered by inactivation or overexpression of various genes involved in the glycerol dissimilation pathways and their individual genetic effects on propionate production were investigated. Generally, knocking out genes involved in glycerol dissimilation (except glpA) can minimize levels of solventogenesis and shift more dissimilated carbon flux toward the C3-fermentative pathway. For optimal propionate production with high C3:C2-fermentative product ratios, glycerol dissimilation should be channeled through the respiratory pathway and, upon suppressed solventogenesis with minimal production of highly reduced alcohols, the alternative NADH-consuming route associated with propionate synthesis can be critical for more flexible redox balancing. With the implementation of various biochemical and genetic strategies, high propionate titers of more than 11 g/L with high yields up to 0.4 g-propionate/g-glycerol (accounting for ~50 % of dissimilated glycerol) were achieved, demonstrating the potential for industrial application. To our knowledge, this represents the most effective engineered microbial system for propionate production with titers and yields comparable to those achieved by anaerobic batch cultivation of various native propionate-producing strains of Propionibacteria. PMID:25948049

  2. Genetic Basis of Persister Tolerance to Aminoglycosides in Escherichia coli

    PubMed Central

    Shan, Yue; Lazinski, David; Rowe, Sarah; Camilli, Andrew

    2015-01-01

    ABSTRACT Persisters are dormant variants that form a subpopulation of drug-tolerant cells largely responsible for the recalcitrance of chronic infections. However, our understanding of the genetic basis of antibiotic tolerance remains incomplete. In this study, we applied transposon sequencing (Tn-Seq) to systematically investigate the mechanism of aminoglycoside tolerance in Escherichia coli. We constructed a highly saturated transposon library that covered the majority of E. coli genes and promoter regions and exposed a stationary-phase culture to a lethal dose of gentamicin. Tn-Seq was performed to evaluate the survival of each mutant to gentamicin exposure. We found that the disruption of several distinct pathways affected gentamicin tolerance. We identified 105 disrupted gene/promoter regions with a more than 5-fold reduction in gentamicin tolerance and 37 genes with a more than 5-fold increased tolerance. Functional cluster analysis suggests that deficiency in motility and amino acid synthesis significantly diminished persisters tolerant to gentamicin, without changing the MIC. Amino acid auxotrophs, including serine, threonine, glutamine, and tryptophan auxotrophs, exhibit strongly decreased tolerance to gentamicin, which cannot be restored by supplying the corresponding amino acids to the culture. Interestingly, supplying these amino acids to wild-type E. coli sensitizes stationary-phase cells to gentamicin, possibly through the inhibition of amino acid synthesis. In addition, we found that the deletion of amino acid synthesis genes significantly increases gentamicin uptake in stationary phase, while the deletion of flagellar genes does not affect gentamicin uptake. We conclude that activation of motility and amino acid biosynthesis contributes to the formation of persisters tolerant to gentamicin. PMID:25852159

  3. Escherichia coli mutants induced by multi-ion irradiation.

    PubMed

    Song, Zhiqing; Luo, Liaofu

    2012-11-01

    Wild-type Escherichia coli K12 strain W3110 was irradiated by 10 keV nitrogen ions. Specifically, irradiation was performed six times by N(+) ions, followed by the selection of lac constitutive mutants, and each time a stable S55 mutant was produced. By sequencing the whole genome, the fine map of S55 was completed. Compared with reference sequences, a total of eighteen single nucleotide polymorphisms (SNPs), two insertions and deletions (Indels), and nine structural variations (SVs) were found in the S55 genome. Among the 18 SNPs, 11 are transversional from A, T or C to G, accounting for 55.6% of point mutations. GCCA insertion occurs in the target gene lacI. Four SNPs, including three in rlpB and one in ygbN, are connected with cell envelope and transport. All nine structural variations of S55 are deletions and contain insertion sequence (IS) elements. Six deleted SVs contain disrupted ISs, nonfunctional pseudogenes, and one more 23 252 bp SV in the Rac prophage region. Overall, our results show that deletion bias observed in E. coli K12 genome evolution is generally related to the deletion of some nonfunctional regions. Furthermore, since ISs are unstable factors in a genome, the multi-ion irradiations that caused these deleted fragments in S55 turn out to be beneficial to genome stability, generating a wider mutational spectrum. Thus, it is possible that the mutation of these genes increases the ability of the E. coli genome to resist etch and damage caused by ion irradiation. PMID:23111758

  4. Antibacterial activity of ?-terpineol may induce morphostructural alterations in Escherichia coli

    PubMed Central

    Li, Li; Shi, Chaofeng; Yin, Zhongqiong; Jia, Renyong; Peng, Lianci; Kang, Shuai; Li, Zhengwen

    2014-01-01

    The antibacterial effect of ?-terpineol from Cinnamomum longepaniculatum (Gamble) N. Chao leaf essential oils were studied with special reference to the mechanism of inhibiting the standard strain of Escherichia coli (CMCC (B) 44102) growth at ultrastructural level. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) and time-kill curves of ?-terpineol were determined; Escherichia coli was treated with ?-terpineol and observed under a transmission electron microscope. The MIC and MBC values of ?-terpineol were all 0.78 ?L/mL, and time-kill curves showed the concentration-dependent. Under the transmission electron microscopy (TEM), Escherichia coli exposed to MIC levels of ?-terpineol exhibited decreased cell size and irregular cell shape, cell wall and cell membrane were ruptured, nucleus cytoplasm was reduced and nuclear area gathered aside. Results suggest that ?-terpineol has excellent antibacterial activity and could induce morphological changes of Escherichia coli. PMID:25763048

  5. Pathway to allostery: differential routes for allosteric communication in phosphofructokinase from Escherichia coli 

    E-print Network

    Paricharttanakul, Nilubol Monique

    2005-02-17

    Phosphofructokinase from Escherichia coli (EcPFK) is allosterically regulated by MgADP and phospho(enol)pyruvate (PEP). Both molecules compete for binding to the same allosteric site, however, MgADP activates and PEP ...

  6. Draft Genome Sequence of Enterotoxigenic Escherichia coli Strain W25K

    PubMed Central

    Ren, Wenkai; Liu, Gang; Yin, Jie; Chen, Shuai; Li, Tiejun; Kong, Xiangfeng; Peng, Yuanyi; Hardwidge, Philip R.

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease in humans and newly weaned pigs. Here, we report the draft genome sequence of ETEC strain W25K, which causes diarrhea in piglets. PMID:24970825

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. COMPARISON OF ESCHERICHIA COLI, TOTAL COLIFORM, AND FECAL COLIFORM POPULATIONS AS INDICATORS OF WASTEWATER TREATMENT EFFICIENCY

    EPA Science Inventory

    Escherichia coli, total coliform, and fecal coliform data were collected from two wastewater treatment facilities, a subsurface constructed wetlands, and the receiving stream. Results are presented from individual wastewater treatment process streams, final effluent and river sit...

  9. Protocol: Precision engineering of plant gene loci by homologous recombination cloning in Escherichia coli

    E-print Network

    Roden, Laura C; Gottgens, Berthold; Mutasa-Gottgens, Effie S

    2005-09-29

    of genetic engineering tools, based on homologous recombination cloning in Escherichia coli, which are free from the constraints imposed by the availability of suitably positioned restriction sites. Here we describe the basis for homologous recombination...

  10. Prevalence and antimicrobial resistance in Escherichia coli from food and animals in Lagos, Nigeria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background Foodborne bacteria are often associated with human infections; these infections can become more complicated to treat if the bacteria are also resistant to antimicrobials. In this study, prevalence, antimicrobial resistance, and genetic relatedness of Escherichia coli among food producing ...

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

    EPA Science Inventory

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

  12. Escherichia coli class Ib ribonucleotide reductase contains a dimanganese(III)-tyrosyl radical cofactor in vivo

    E-print Network

    Cotruvo, Joseph Alfred

    Escherichia coli class Ib ribonucleotide reductase (RNR) converts nucleoside 5?-diphosphates to deoxynucleoside 5?-diphosphates in iron-limited and oxidative stress conditions. We have recently demonstrated in vitro that ...

  13. An active dimanganese(III)-tyrosyl radical cofactor in Escherichia coli class Ib ribonucleotide reductase

    E-print Network

    Cotruvo, Joseph Alfred

    Escherichia coli class Ib ribonucleotide reductase (RNR) converts nucleoside 5?-diphosphates to deoxynucleoside 5?-diphosphates and is expressed under iron-limited and oxidative stress conditions. This RNR is composed of ...

  14. DETOXIFICATION OF ORGANOPHOSPHATE PESTICIDES BY IMMOBILIZED ESCHERICHIA COLI EXPRESSING ORGANOPHOSPHORUS HYDROLASE ON CELL SURFACE. (R823663)

    EPA Science Inventory

    An improved whole-cell technology for detoxifying organophosphate nerve agents was recently developed based on genetically engineered Escherichia coli with organophosphorus hydrolase anchored on the surface. This article reports the immobilization of these novel biocatalys...

  15. Novel function and regulation of mutagenic DNA polymerases in Escherichia coli

    E-print Network

    Jarosz, Daniel F

    2007-01-01

    The observation that mutations in the Escherichia coli genes umuC+ and umuD+ abolish mutagenesis induced by UV-light strongly supported the counterintuitive notion that such mutagenesis is an active rather than passive ...

  16. Insights on Escherichia coli biofilm formation and inhibition from whole-transcriptome profiling

    E-print Network

    Wood, Thomas K.

    Minireview Insights on Escherichia coli biofilm formation and inhibition from whole University, College Station, TX 77843-3122, USA. Summary Biofilms transform independent cells into specialized cell communities. Here are presented some insights into biofilm formation ascertained

  17. Effect of natural antimicrobials against Salmonella, Escherichia coli o157:h7 and Listeria monocytogenes 

    E-print Network

    Cuervo Pliego, Mary Pia

    2009-05-15

    Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes are pathogens that have caught the attention of federal agencies and researchers due to their great economic impact when illnesses occur. To reduce the presence of these pathogens...

  18. IMPACT OF MICROBIAL DIVERSITY ON RAPID DETECTION OF ENTEROHEMORRHAGIC ESCHERICHIA COLI IN SURFACE WATERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enterohemorrhagic Escherichia coli are a physiologically, immunologically and genetically diverse collection of strains that pose a serious water-borne threat to human health. Consequently, rapid assays are needed that consistently detect water-borne enterohemorrhagic strains while excluding closel...

  19. Importance of the Maintenance Pathway in the Regulation of the Activity of Escherichia coli Ribonucleotide Reductase

    E-print Network

    Hristova, Daniela

    Ribonucleotide reductases (RNRs) catalyze the conversion of nucleotides to deoxynucleotides in all organisms. The Escherichia coli class Ia RNR is composed of ? and ? subunits that form an ?[subscript 2]?[subscript 2] ...

  20. ‹drar Örneklerinden ‹zole Edilen Toplum ve Hastane Kaynakl› Escherichia coli Sufllar›nda Antibiyotik Direnci

    Microsoft Academic Search

    Füsun Zeynep; Onur KAYA; Güler YAYLI

    2004-01-01

    Gerek toplum kaynakl› gerekse hastane kaynakl› üriner sistem infeksiyonlar›nda en s›k izo- le edilen etken Escherichia coli'dir. Bu çal›flma, bölgemizdeki Escherichia coli sufllar›n›n çe- flitli antibiyotiklere direnç durumlar›n›n belirlenmesi ve ampirik tedavi seçeneklerinde yol gösterici olmas› amac›yla yap›lm›flt›r. 129 toplum kökenli, 120 hastane kökenli suflun, \\

  1. Cloning of an endoglucanase gene from Pseudomonas fluorescens var. cellulosa into Escherichia coli and Pseudomonas fluorescens

    Microsoft Academic Search

    André Lejeune; Charles Colson; Douglas E. Eveleigh

    1986-01-01

    Summary An endoglucanase chromosomal gene from the cellulolyticPseudomonas fluorescens var.cellulosa (NCIB 10462) was cloned inEscherichia coli. Chromosomal DNA was partially digested with the restriction enzymeEcoRI and ligated into the broad host-range, mobilizable plasmid pSUP104 that had been linearized with the same enzyme. After transformation ofEscherichia coli, and endoglucanase-positive clone was detected in situ by use of the Congo-red assay procedure.

  2. Direction of Chain Elongation in the Formation of Escherichia coli Ribosomal Protein

    Microsoft Academic Search

    Sun Ao Iwata; Hideko Kaji

    1971-01-01

    Ribosomal proteins were isolated from logarithmically growing Escherichia coli cells given [14C]-alanine for short periods. Surprisingly, the specific activity of alanine at the NH2-terminal end was higher than that of alanine released by carboxypeptidase A digestion of the ribosomal protein. To determine the direction of chain elongation more precisely, Escherichia coli cells were grown with [3H]amino acids, and [14C]amino acids

  3. A new plasmidic cefotaximase in a clinical isolate of Escherichia coli

    Microsoft Academic Search

    A. Bauernfeind; S. Schweighart; H. Grimm

    1990-01-01

    Summary Escherichia coli GRI was isolated from an ear exudate of a newborn. The strain was highly resistant to cefotaxime (MIC 128 mg\\/l). Resistance to cefotaxime and the majority of ß-lactam antibiotics was readily transferred to anEscherichia coli recipient strain. Both the wild type and the transconjugant strains are different in their resistance phenotype from TEM-3 ß-cefotaximase producers by higher

  4. Effects of essential oils from medicinal plants used in Brazil against epec and etec Escherichia coli

    Microsoft Academic Search

    C. Delarmelina; G. M. Figueira

    Effects of essential oils from medicinal plants used in brazil against epec and etec escherichia coli . Essential oils obtained from leaves of 28 medicinal plants commonly used in Brazil were screened against anti- enteropathogenic (EPEC) and anti-enterotoxigenic (ETEC) Escherichia coli. The oils were obtained by water-distillation using a Clevenger-type system and their Minimal Inhibitory Concentration (MIC) was determined. Among

  5. Low intensity infrared laser effects on Escherichia coli cultures and plasmid DNA

    NASA Astrophysics Data System (ADS)

    Fonseca, A. S.; Teixeira, A. F.; Presta, G. A.; Geller, M.; Valença, S. S.; Paoli, F.

    2012-10-01

    Biostimulative effect of low intensity laser in tissues has been described on a photobiological basis and clinical protocols are recommended for treatment of various diseases. The aim of this work was to evaluate effects of laser exposure on the survival of Escherichia coli cultures and plasmid topological forms. Escherichia coli cultures and plasmids were exposed to infrared laser to study bacterial survival and electrophoretic profile, respectively. Data indicate low intensity infrared laser: (i) had no effect on E. coli wild type, endonuclease IV, exonuclease III, formamidopyrimidine DNA glycosylase/MutM protein and endonuclease III deficient cultures, but decreased the survival of E. coli UvrA protein deficient cultures; (ii) there was no alteration in the electrophoretic profile of plasmids. Exposure to low intensity infrared laser decreases survival of Escherichia coli cultures deficient in nucleotide excision repair of DNA and this effect could depend on fluences, wavelength and tissues conditions.

  6. Pathogenesis of Afa/Dr Diffusely Adhering Escherichia coli

    PubMed Central

    Servin, Alain L.

    2005-01-01

    Over the last few years, dramatic increases in our knowledge about diffusely adhering Escherichia coli (DAEC) pathogenesis have taken place. The typical class of DAEC includes E. coli strains harboring AfaE-I, AfaE-II, AfaE-III, AfaE-V, Dr, Dr-II, F1845, and NFA-I adhesins (Afa/Dr DAEC); these strains (i) have an identical genetic organization and (ii) allow binding to human decay-accelerating factor (DAF) (Afa/DrDAF subclass) or carcinoembryonic antigen (CEA) (Afa/DrCEA subclass). The atypical class of DAEC includes two subclasses of strains; the atypical subclass 1 includes E. coli strains that express AfaE-VII, AfaE-VIII, AAF-I, AAF-II, and AAF-III adhesins, which (i) have an identical genetic organization and (ii) do not bind to human DAF, and the atypical subclass 2 includes E. coli strains that harbor Afa/Dr adhesins or others adhesins promoting diffuse adhesion, together with pathogenicity islands such as the LEE pathogenicity island (DA-EPEC). In this review, the focus is on Afa/Dr DAEC strains that have been found to be associated with urinary tract infections and with enteric infection. The review aims to provide a broad overview and update of the virulence aspects of these intriguing pathogens. Epidemiological studies, diagnostic techniques, characteristic molecular features of Afa/Dr operons, and the respective role of Afa/Dr adhesins and invasins in pathogenesis are described. Following the recognition of membrane-bound receptors, including type IV collagen, DAF, CEACAM1, CEA, and CEACAM6, by Afa/Dr adhesins, activation of signal transduction pathways leads to structural and functional injuries at brush border and junctional domains and to proinflammatory responses in polarized intestinal cells. In addition, uropathogenic Afa/Dr DAEC strains, following recognition of ?1 integrin as a receptor, enter epithelial cells by a zipper-like, raft- and microtubule-dependent mechanism. Finally, the presence of other, unknown virulence factors and the way that an Afa/Dr DAEC strain emerges from the human intestinal microbiota as a “silent pathogen” are discussed. PMID:15831825

  7. Scalable production of biliverdin IX? by Escherichia coli

    PubMed Central

    2012-01-01

    Background Biliverdin IX? is produced when heme undergoes reductive ring cleavage at the ?-methene bridge catalyzed by heme oxygenase. It is subsequently reduced by biliverdin reductase to bilirubin IX? which is a potent endogenous antioxidant. Biliverdin IX?, through interaction with biliverdin reductase, also initiates signaling pathways leading to anti-inflammatory responses and suppression of cellular pro-inflammatory events. The use of biliverdin IX? as a cytoprotective therapeutic has been suggested, but its clinical development and use is currently limited by insufficient quantity, uncertain purity, and derivation from mammalian materials. To address these limitations, methods to produce, recover and purify biliverdin IX? from bacterial cultures of Escherichia coli were investigated and developed. Results Recombinant E. coli strains BL21(HO1) and BL21(mHO1) expressing cyanobacterial heme oxygenase gene ho1 and a sequence modified version (mho1) optimized for E. coli expression, respectively, were constructed and shown to produce biliverdin IX? in batch and fed-batch bioreactor cultures. Strain BL21(mHO1) produced roughly twice the amount of biliverdin IX? than did strain BL21(HO1). Lactose either alone or in combination with glycerol supported consistent biliverdin IX? production by strain BL21(mHO1) (up to an average of 23. 5mg L-1 culture) in fed-batch mode and production by strain BL21 (HO1) in batch-mode was scalable to 100L bioreactor culture volumes. Synthesis of the modified ho1 gene protein product was determined, and identity of the enzyme reaction product as biliverdin IX? was confirmed by spectroscopic and chromatographic analyses and its ability to serve as a substrate for human biliverdin reductase A. Conclusions Methods for the scalable production, recovery, and purification of biliverdin IX? by E. coli were developed based on expression of a cyanobacterial ho1 gene. The purity of the produced biliverdin IX? and its ability to serve as substrate for human biliverdin reductase A suggest its potential as a clinically useful therapeutic. PMID:23176158

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

    PubMed

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

    2010-04-15

    The prevalence of diarrheagenic Escherichia coli in childhood diarrhea and the role of contaminated food products in disease transmission in Colombia are largely unknown. The aim of this study is to identify E. coli pathotypes, including E. coli O157:H7, from 108 stool samples from children with acute diarrhea, 38 meat samples and 38 vegetable samples. Multiplex PCR and Bax Dupont systems were used for E. coli pathotype detection. Eighteen (9.8%) E. coli diarrheagenic pathotypes were detected among all clinical and food product samples tested. Four different pathotypes were identified from clinical samples, including enteroaggregative E. coli, enterotoxigenic E. coli, shiga-toxin producing E. coli, and enteropathogenic E. coli. Food product samples were positive for enteroaggregative and shiga-toxin producing E. coli, suggesting that meat and vegetables may be involved in transmission of these E. coli pathotypes in the community. Most E. coli strains identified belong to the phylogenetic groups A and B1, known to be associated with intestinal rather than extraintestinal E. coli clones. Our data is the first molecular E. coli report that confirms the presence of E. coli pathotypes circulating in Colombia among children with diarrhea and food products for human consumption. Implementation of multiplex PCR technology in Latin America and other countries with limited resources may provide an important epidemiological tool for the surveillance of E. coli pathotypes from clinical isolates as well as from water and food product samples. PMID:20153069

  9. The Genome Sequence of Avian Pathogenic Escherichia coli Strain O1:K1:H7 Shares Strong Similarities with Human Extraintestinal Pathogenic E. coli Genomes

    Microsoft Academic Search

    Timothy J. Johnson; Subhashinie Kariyawasam; Yvonne Wannemuehler; Paul Mangiamele; Sara J. Johnson; Curt Doetkott; Jerod A. Skyberg; Aaron M. Lynne; James R. Johnson; Lisa K. Nolan

    2007-01-01

    Escherichia coli strains that cause disease outside the intestine are known as extraintestinal pathogenic E. coli (ExPEC) and include human uropathogenic E. coli (UPEC) and avian pathogenic E. coli (APEC). Regard- less of host of origin, ExPEC strains share many traits. It has been suggested that these commonalities may enable APEC to cause disease in humans. Here, we begin to

  10. Prevalence and geographical distribution of Escherichia coli O157 in India: a 10-year survey.

    PubMed

    Sehgal, Rakesh; Kumar, Yashwant; Kumar, Sunil

    2008-04-01

    Escherichia coli colonizes the human gastrointestinal tract and produces a variety of diseases. Escherichia coli O157 is one of the most important pathogenic strains reported from food-borne illnesses leading to enterohemorrhagic colitis. The National Salmonella and Escherichia Centre is a national reference centre for Salmonella and Escherichia for India; it receives samples from research laboratories, hospitals and institutions for serological identification. The present study is an epidemiological survey of E. coli O157 in different regions of India. The data are based on samples received from humans, food items, animals and the environment. A total of 17 093 isolates cultured from samples were received during the 10-year period of which 5678 were from human sources. Thirty (0.5%) human samples were positive for E. coli O157. A significantly high percentage of E. coli O157 were isolated from meat (0.9%, 13/1376), milk and milk products (1.8%, 10/553), seafood (8.4%, 16/190) and water (1.6%, 8/486). The isolates were found to be distributed among domestic and wild animals, and the maximum number of isolates of E. coli O157 was detected in samples received from coastal belt areas. Escherichia coli O157 is widely distributed among humans and animals, food and environment in different geographical regions of India. PMID:18321544

  11. Fungal ?-1,3-Glucan Increases Ofloxacin Tolerance of Escherichia coli in a Polymicrobial E. coli/Candida albicans Biofilm.

    PubMed

    De Brucker, Katrijn; Tan, Yulong; Vints, Katlijn; De Cremer, Kaat; Braem, Annabel; Verstraeten, Natalie; Michiels, Jan; Vleugels, Jef; Cammue, Bruno P A; Thevissen, Karin

    2015-06-01

    In the past, biofilm-related research has focused mainly on axenic biofilms. However, in nature, biofilms are often composed of multiple species, and the resulting polymicrobial interactions influence industrially and clinically relevant outcomes such as performance and drug resistance. In this study, we show that Escherichia coli does not affect Candida albicans tolerance to amphotericin or caspofungin in an E. coli/C. albicans biofilm. In contrast, ofloxacin tolerance of E. coli is significantly increased in a polymicrobial E. coli/C. albicans biofilm compared to its tolerance in an axenic E. coli biofilm. The increased ofloxacin tolerance of E. coli is mainly biofilm specific, as ofloxacin tolerance of E. coli is less pronounced in polymicrobial E. coli/C. albicans planktonic cultures. Moreover, we found that ofloxacin tolerance of E. coli decreased significantly when E. coli/C. albicans biofilms were treated with matrix-degrading enzymes such as the ?-1,3-glucan-degrading enzyme lyticase. In line with a role for ?-1,3-glucan in mediating ofloxacin tolerance of E. coli in a biofilm, we found that ofloxacin tolerance of E. coli increased even more in E. coli/C. albicans biofilms consisting of a high-?-1,3-glucan-producing C. albicans mutant. In addition, exogenous addition of laminarin, a polysaccharide composed mainly of poly-?-1,3-glucan, to an E. coli biofilm also resulted in increased ofloxacin tolerance. All these data indicate that ?-1,3-glucan from C. albicans increases ofloxacin tolerance of E. coli in an E. coli/C. albicans biofilm. PMID:25753645

  12. Effects of intravenous Escherichia coli dose on the pathophysiological response of colostrum-fed Jersey calves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objectives of the present study were to characterize the dose dependency of an intravenous Escherichia coli (E. coli) challenge in colostrum-fed Jersey calves and to identify biochemical markers indicative of septicemia. Eighteen 3-wk old colostrum-fed Jersey calves were completely randomized to 1 o...

  13. Expression Analysis of Up-Regulated Genes Responding to Plumbagin in Escherichia coli

    Microsoft Academic Search

    Jenn-Wei Chen; Chang-Ming Sun; Wei-Lun Sheng; Yu-Chen Wang; Wan-Jr Syu

    2006-01-01

    Plumbagin is found in many medicinal plants and has been reported to have antimicrobial activities. We examined the molecular responses of Escherichia coli to plumbagin by using a proteomic approach to search for bacterial genes up-regulated by the drug. The protein profile obtained was compared with that of E. coli without the plumbagin treatment. Subsequent analyses of the induced proteins

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

    E-print Network

    Selinger, Brent

    Prevalence of Escherichia coli O157:H7 and Salmonella spp. in surface waters of southern Alberta and Salmonella spp. in surface water within the basin. This study is the first of its kind to identify E. coli O and Salmonella spp. in water samples was 0.9% (n = 1483) and 6.2% (n = 1429), respectively. While data examined

  15. Survival of Escherichia coli 0157 in a soil protozoan: implications for disease

    Microsoft Academic Search

    John Barker; Tom J Humphrey; Michael W. R Brown

    1999-01-01

    Intra-protozoal growth of bacterial pathogens has been associated with increased environmental survival, virulence and resistance to biocides and antibiotics. Using laboratory microcosms we have shown that Escherichia coli 0157 survives and replicates in a common environmental protozoan, Acanthamoeba polyphaga. As protozoa are widely distributed in soils and effluents, they may constitute an important environmental reservoir for transmission of E. coli

  16. Self-Organization of the Escherichia coli Chemotaxis Network Imaged with Super-Resolution Light Microscopy

    Microsoft Academic Search

    Derek Greenfield; Ann L. McEvoy; Hari Shroff; Gavin E. Crooks; Ned S. Wingreen; Eric Betzig; Jan Liphardt

    2009-01-01

    The Escherichia coli chemotaxis network is a model system for biological signal processing. In E. coli, transmembrane receptors responsible for signal transduction assemble into large clusters containing several thousand proteins. These sensory clusters have been observed at cell poles and future division sites. Despite extensive study, it remains unclear how chemotaxis clusters form, what controls cluster size and density, and

  17. Expression in Escherichia coli of the native cyt1Aa from Bacillus thuringiensis subsp. israelensis.

    PubMed

    Sazhenskiy, Vladislav; Zaritsky, Arieh; Itsko, Mark

    2010-05-01

    The gene cyt1Aa is one of the genes in the complex determining the mosquito larvicidity of Bacillus thuringiensis subsp. israelensis. Previous cloning in Escherichia coli resulted in a 48-bp addition upstream, encoding a chimera. Here, cyt1Aa was recloned without the artifact, and its toxicity against Aedes aegypti larvae and host E. coli cells was retested. PMID:20348307

  18. DETECTION OF ESCHERICHIA COLI IN WATER USING A COLORIMETRIC GENE PROBE ASSAY

    EPA Science Inventory

    A commercially available DNA hydribization assay (Gene-trak , Framingham, MA. USA) was compared with the EC-MUG procedure for the detection of Escherichia coli in water. The gene probe gave positive responses for pure cultures of E. coli 0157:H7, E. fergusonii, Shigella sonnei, S...

  19. Biofilm formation as a novel phenotypic feature of adherent-invasive Escherichia coli (AIEC)

    Microsoft Academic Search

    Margarita Martinez-Medina; Plínio Naves; Jorge Blanco; Xavier Aldeguer; Jesus E Blanco; Miguel Blanco; Carmen Ponte; Francisco Soriano; Arlette Darfeuille-Michaud; L Jesus Garcia-Gil

    2009-01-01

    BACKGROUND: Crohn's disease (CD) is a high morbidity chronic inflammatory disorder of unknown aetiology. Adherent-invasive Escherichia coli (AIEC) has been recently implicated in the origin and perpetuation of CD. Because bacterial biofilms in the gut mucosa are suspected to play a role in CD and biofilm formation is a feature of certain pathogenic E. coli strains, we compared the biofilm

  20. Proteomic analysis reveals protein expression differences in Escherichia coli strains associated with persistent versus transient mastitis

    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, causing an infection that lasts 2-3 days. However, in a minority of cases, E. coli has been shown to cause a persistent intramammary infection. The mechanisms that allow for...

  1. Physical Basis of Metal-Binding Specificity in Escherichia coli NikR

    E-print Network

    Phillips, Christine M.

    In Escherichia coli and other bacteria, nickel uptake is regulated by the transcription factor NikR. Nickel binding at high-affinity sites in E. coli NikR (EcNikR) facilitates EcNikR binding to the nik operon, where it ...

  2. PERSISTENCE OF ESCHERICHIA COLI O157:H7 IN SOIL AFTER FUMIGATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long term persistence of Escherichia 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 runoffs. Multi...

  3. Surveillance for Shiga Toxin–producing Escherichia coli, Michigan, 2001–2005

    PubMed Central

    Manning, Shannon D.; Madera, Robbie T.; Schneider, William; Dietrich, Stephen E.; Khalife, Walid; Brown, William; Whittam, Thomas S.; Somsel, Patricia

    2007-01-01

    A surveillance system used different detection methods to estimate prevalence of Shiga toxin–producing Escherichia coli during 2003–2005 and 2001–2002. More non-O157 serotypes were detected by enzyme immunoassay than by evaluation of non-sorbitol–fermenting E. coli isolates. We therefore recommend use of enzyme immunoassay and culture-based methods. PMID:17479902

  4. Surveillance for Shiga toxin-producing Escherichia coli, Michigan, 2001-2005.

    PubMed

    Manning, Shannon D; Madera, Robbie T; Schneider, William; Dietrich, Stephen E; Khalife, Walid; Brown, William; Whittam, Thomas S; Somsel, Patricia; Rudrik, James T

    2007-02-01

    A surveillance system used different detection methods to estimate prevalence of Shiga toxin-producing Escherichia coli during 2003-2005 and 2001-2002. More non-O157 serotypes were detected by enzyme immunoassay than by evaluation of non-sorbitol-fermenting E. coli isolates. We therefore recommend use of enzyme immunoassay and culture-based methods. PMID:17479902

  5. Effect of copper hydroxide sprays for citrus canker control on wild type Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies were performed in vitro with bacteria grown in broth and then subjected to the same copper hydroxide concentrations as are sprayed on citrus trees in Florida throughout the growing season. Studies were also undertaken with grapefruit leaves and the survival of Escherichia coli (E. coli) on t...

  6. Proliferation of Escherichia coli O157:H7 in soil and hydroponic microgreen production systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Radish (Raphanus sativus var. longipinnatus) microgreens were produced from seeds inoculated with Escherichia coli O157: H7 using soil substitute and hydroponic production systems. E. coli populations on the edible and inedible parts of harvested microgreen plants and in growth medium were examined....

  7. Principales características y diagnóstico de los grupos patógenos de Escherichia coli

    Microsoft Academic Search

    Guadalupe Rodríguez-Angeles

    2002-01-01

    Escherichia coli colonizes the human intestinal tract within hours of birth and is considered a non-pathogenic member of the normal intestinal flora. However, there are six pathogenic groups that may produce diarrhea: enteroto- xigenic (ETEC), enterohemorrhagic (EHEC), enteroinvasive (EIEC), enteropathogenic (EPEC), enteroaggregative (EAEC) and diffusely adherent (DAEC) groups. E. coli can be isolated and classified using traditional methods, by identifying

  8. Phylogeny, virulence factors and antimicrobial susceptibility of Escherichia coli isolated in clinical bovine mastitis

    Microsoft Academic Search

    Leena Suojala; Tarja Pohjanvirta; Heli Simojoki; Anna-Liisa Myllyniemi; Anna Pitkälä; Sinikka Pelkonen; Satu Pyörälä

    2011-01-01

    The aim of this study was to identify specific phylogeny groups, virulence genes or antimicrobial resistance traits of Escherichia coli isolated in bovine mastitis associated to clinical signs, persistence of intramammary infection in the quarter and recovery from mastitis. A total of 154 E. coli isolates from bovine clinical mastitis, 144 from the acute stage and 10 from follow-up samples

  9. Growth and survival of Escherichia coli and enterococci populations in the macro-alga Cladophora (Chlorophyta)

    Microsoft Academic Search

    Muruleedhara N Byappanahalli; Dawn A Shively; Meredith B Nevers; Michael J Sadowsky; Richard L Whitman

    2003-01-01

    The macro-alga Cladophora glomerata is found in streams and lakes worldwide. High concentrations of Escherichia coli and enterococci have been reported in Cladophora along the Lake Michigan shore. The objective of this study was to determine if Cladophora supported growth of these indicator bacteria. Algal leachate readily supported in vitro multiplication of E. coli and enterococci, suggesting that leachates contain

  10. Draft Genome Sequence of Escherichia coli Strain LCT-EC59

    PubMed Central

    Li, Tianzhi; Chen, Jiapeng; Chang, De; Fang, Xiangqun; Wang, Junfeng; Guo, Yinghua; Su, Longxiang; Xu, Guogang; Wang, Yajuan; Chen, Zhenhong

    2013-01-01

    The space environment is a very special condition under which many organisms change many features. Escherichia coli is employed widely as a prokaryotic model organism in the fields of biotechnology and microbiology. Here, we present the draft genome sequence of E. coli strain LCT-EC59 exposed to space conditions. PMID:23469355

  11. Movement and treatment of water containing Escherichia coli applied to soil by subsurface drip emitters 

    E-print Network

    Franti, Jason M

    2001-01-01

    in regards to the reduction of Escherichia coli in wastewater that reaches the soil surface and the number of instances of wastewater surfacing in these clayey soils. Water colored with a dye and inoculated with E. coli was applied to soil through drip...

  12. Proteome Analysis of Metabolically Engineered Escherichia coli Producing Poly(3-Hydroxybutyrate)

    Microsoft Academic Search

    MEE-JUNG HAN; SANG SUN YOON; SANG YUP LEE

    2001-01-01

    Recombinant Escherichia coli strains harboring heterologous polyhydroxyalkanoate (PHA) biosynthesis genes were shown to accumulate unusually large amounts of PHA. In the present study, integrated cellular responses of metabolically engineered E. coli to the accumulation of poly(3-hydroxybutyrate) (PHB) in the early stationary phase were analyzed at the protein level by two-dimensional gel electrophoresis. Out of 20 proteins showing altered expression levels

  13. Distribution of Escherichia coli passage through processing equipment during ground beef production using inoculated trim

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The contamination of raw ground beef by Escherichia coli O157:H7 is not only a public health issue but also an economic concern to meat producers. When E. coli O157:H7 is detected in ground beef, products made immediately before and after the positive sample are discarded or diverted to lethality t...

  14. FACTORS AFFECTING ATTACHMENT OF ESCHERICHIA COLI O157:H7 TO APPLE TISSUES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Attachment of Escherichia coli O157:H7 and fluorescent microspheres to the stem, calyx sepals, russet and discontinuities on the skin of Golden Delicious apples was investigated. Attachment of the E. coli cells to the stems resulted in their removal from the inoculum solution over time where the ce...

  15. Efficacy of supercritical carbon dioxide for nonthermal inactivation of Escherichia coli K12 in apple cider

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the efficacy of a supercritical carbon dioxide (SCCO2) system with a gas-liquid porous metal contactor for eliminating Escherichia coli K12 in apple cider. Pasteurized, preservative-free apple cider was inoculated with E. coli K12 and processed using the SCCO2 system at CO2 conc...

  16. Human Response to Escherichia coli O157:H7 Infection: Antibodies to Secreted Virulence Factors

    Microsoft Academic Search

    YULING LI; ELIZABETH FREY; ANDREW M. R. MACKENZIE; B. BRETT FINLAY

    2000-01-01

    Vaccination has been proposed for the prevention of disease due to enterohemorrhagic Escherichia coli (EHEC), but the immune response following human infection, including the choice of potential antigens, has not been well characterized. To study this, sera were obtained from five pediatric patients with acute diarrhea caused by E. coli O157:H7 0, 8, and 60 days after hospitalization. These sera

  17. Analysis of Genome Plasticity in Pathogenic and Commensal Escherichia coli Isolates by Use of DNA Arrays

    Microsoft Academic Search

    Ulrich Dobrindt; Franziska Agerer; Kai Michaelis; Andreas Janka; Carmen Buchrieser; Martin Samuelson; Catharina Svanborg; Gerhard Gottschalk; Helge Karch; Jorg Hacker

    2003-01-01

    Genomes of prokaryotes differ significantly in size and DNA composition. Escherichia coli is considered a model organism to analyze the processes involved in bacterial genome evolution, as the species comprises numerous pathogenic and commensal variants. Pathogenic and nonpathogenic E. coli strains differ in the presence and absence of additional DNA elements contributing to specific virulence traits and also in the

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

    E-print Network

    Singer, Randall

    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 of the broiler house, we designed a study to determine whether E. coli DNA ®ngerprints associated with cellulitis

  19. Macromolecule Mediated Transport and Retention of Escherichia coli O157:H7 in Saturated Porous Media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The role of extracellular macromolecules on Escherichia coli O157:H7 transport and retention was investigated in saturated porous media. To compare the relative transport and retention of E. coli cells that are macromolecule rich and deficient, macromolecules were partially cleaved using a proteolyt...

  20. Sm-like proteins in Eubacteria: the crystal structure of the Hfq protein from Escherichia coli

    Microsoft Academic Search

    Claude Sauter; Jerome Basquin; Dietrich Suck

    2003-01-01

    The Hfq protein was discovered in Escherichia coli in the early seventies as a host factor for the Qb phage RNA replication. During the last decade, it was shown to be involved in many RNA processing events and remote sequence homology indicated a link to spliceosomal Sm proteins. We report the crystal structure of the E.coli Hfq protein showing that

  1. Metabolic flux analysis of Escherichia coli MG1655 under octanoic acid (C8) stress

    Microsoft Academic Search

    Yanfen Fu

    2011-01-01

    Metabolic engineering has evolved to the point of fulfilling the dream of having industrial chemicals produced renewably. Carboxylic acids [e.g., short chain fatty acids (SCFAs) such as octanoic acid (C8)] are such chemical intermediates that can be produced by Escherichia coli engineered with thioesterases specific for short chain fatty acids. However, C8 is toxic to E. coli at concentration greater

  2. Movement and treatment of water containing Escherichia coli applied to soil by subsurface drip emitters

    E-print Network

    Franti, Jason M

    2001-01-01

    in regards to the reduction of Escherichia coli in wastewater that reaches the soil surface and the number of instances of wastewater surfacing in these clayey soils. Water colored with a dye and inoculated with E. coli was applied to soil through drip...

  3. Efficacy of Cefquinome for Treatment of Cows with Mastitis Experimentally Induced Using Escherichia coli

    Microsoft Academic Search

    N. Y. Shpigel; D. Levin; M. Winkler; A. Saran; G. Ziv; A. Böttner

    1997-01-01

    The efficacy of intramuscularly and intramammar- ily administered cefquinome was evaluated in ex- perimental Escherichia coli mastitis in dairy cows. Forty-seven multiparous, Israeli Holstein cows in early lactation that produced at least 25 L\\/d of milk were used, and 400 to 750 cfu of E. coli were infused into two healthy quarters of each cow. Cows were randomly assigned to

  4. Role of Nonhost Environments in the Lifestyles of Salmonella and Escherichia coli

    Microsoft Academic Search

    Mollie D. Winfield; Eduardo A. Groisman

    2003-01-01

    The gram-negative bacterial species Salmonella enterica and Escherichia coli are members of the family Enterobacteriaceae that spend a good part of their lives as residents of animal hosts. S. enterica is the etiologic agent of gastroenteritis and typhoid fever in humans (88), whereas E. coli is most com- monly known as a commensal of the lower intestine of mam- mals,

  5. MazG, a Nucleoside Triphosphate Pyrophosphohydrolase, Interacts with Era, an Essential GTPase in Escherichia coli

    Microsoft Academic Search

    Junjie Zhang; Masayori Inouye

    2002-01-01

    Era is an essential GTPase in Escherichia coli, and Era has been implicated in a number of cellular functions. Homologues of Era have been identified in various bacteria and some eukaryotes. Using the era gene as bait in the yeast two-hybrid system to screen E. coli genomic libraries, we discovered that Era interacts with MazG, a protein of unknown function

  6. Escherichia coli Regrowth and Macroinvertebrate Health in Urban and Rural Streams

    E-print Network

    McCrary, Kathryn Jordan

    2012-07-16

    of indicator bacteria, Escherichia coli. This study collected data on the recovery and regrowth of E. coli by collecting ultraviolet light treated effluent from the Carters Creek WWTP and spiked it with three different concentrations of DOC derived from a leaf...

  7. Identification of Escherichia coli O157 by Using a Novel Colorimetric Detection Method with DNA Microarrays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin-producing Escherichia coli O157:H7 is a leading cause of foodborne illness worldwide. To evaluate better methods to rapidly detect and genotype E. coli O157 strains, the present study evaluated the use of ampliPHOX, a novel colorimetric detection method based on photopolymerization, for...

  8. Phagocytic and oxidative burst activity of chicken thrombocytes to Salmonella, Escherichia coli and other bacteria

    Microsoft Academic Search

    Paul Wigley; Scott D. Hulme; Paul A. Barrow

    1999-01-01

    The potential role of chicken thrombocytes in immune responses to Salmonella, Escherichia coli and other bacteria was investigated by in vitro assays of phagocytosis and respiratory burst activity. Thrombocytes were found to phagocytose bacteria, but were found to be less phagocytic than heterophils. Oxidative burst activity was generated upon challenge of thrombocytes with various Salmonella strains, E. coli, three other

  9. Effect of ozone on metabolic activities of Escherichia coli K-12

    Microsoft Academic Search

    Indira Ruth Komanapalli; John Brian Mudd; Benjamin H. S. Lau

    1997-01-01

    Escherichia coli K-12 cell suspensions in buffer were exposed to ozone at a concentration of 600 ppm. Measurements were made of cell viability, glyceraldehyde-3-phosphate dehydrogenase, malate dehydrogenase, lactate dehydrogenase, glutathione disulfide reductase, nonprotein sulfhydryl and total sulfhydryl compounds. Cell viability was not affected when E. coli K-12 was exposed to ozone for less than 10 minutes. The most sensitive parameter

  10. Functional Genomics: Expression Analysis of Escherichia coli Growing on Minimal and Rich Media

    Microsoft Academic Search

    HAN TAO; CHRISTOPH BAUSCH; CRAIG RICHMOND; FREDERICK R. BLATTNER

    DNA arrays of the entire set of Escherichia coli genes were used to measure the genomic expression patterns of cells growing in late logarithmic phase on minimal glucose medium and on Luria broth containing glucose. Ratios of the transcript levels for all 4,290 E. coli protein-encoding genes (cds) were obtained, and analysis of the expression ratio data indicated that the

  11. Embedded DNA-polypyrrole biosensor for rapid detection of Escherichia Coli

    Microsoft Academic Search

    Maria I. Rodríguez; Evangelyn C. Alocilja

    2005-01-01

    The principal objective of this paper was to present the design and fabrication of a single-strand (ss) DNA biosensor for the detection of Escherichia coli (E. coli) DNA synthetic oligonucleotides as a model of rapid detection of bacterial select bioterrorism agents. Molecular biology and chemical electrodeposition techniques, such as cyclic voltammetry (CV), were combined to develop and test a model

  12. Extensive Genomic Diversity in Pathogenic Escherichia coli and Shigella Strains Revealed by Comparative Genomic Hybridization Microarray

    Microsoft Academic Search

    Satoru Fukiya; Hiroshi Mizoguchi; Toru Tobe; Hideo Mori

    2004-01-01

    Escherichia coli, including the closely related genus Shigella, is a highly diverse species in terms of genome structure. Comparative genomic hybridization (CGH) microarray analysis was used to compare the gene content of E. coli K-12 with the gene contents of pathogenic strains. Missing genes in a pathogen were detected on a microarray slide spotted with 4,071 open reading frames (ORFs)

  13. Development of a Procedure for Discriminating among Escherichia coli Isolates from Animal and Human Sources

    Microsoft Academic Search

    Shukui Guan; Renlin Xu; Shu Chen; Joseph Odumeru; Carlton Gyles

    2002-01-01

    Counts of Escherichia coli cells in water indicate the potential presence of pathogenic microbes of intestinal origin but give no indication of the sources of the microbial pollution. The objective of this research was to evaluate methods for differentiating E. coli isolates of livestock, wildlife, or human origin that might be used to predict the sources of fecal pollution of

  14. Catabolite repression in Escherichia coli. A study of two hypotheses

    PubMed Central

    Moses, V.; Yudkin, M. D.

    1968-01-01

    1. Two hypotheses to account for general catabolite repression of the lactose enzymes in Escherichia coli were tested: the dilution model of Palmer & Moses (1967), and the specific catabolite repressor model of Loomis & Magasanik (1965, 1967). 2. The dilution model predicts that in mutants lacking the i–o regulation system the differential rate of ?-galactosidase synthesis should increase when amino acid-synthesizing enzymes are repressed by the presence of amino acids in the medium. It also predicts that with such mutants the total absence of Pi from the medium should not result in the complete cessation of ?-galactosidase synthesis that is observed with wild-type cells. 3. Neither prediction was confirmed experimentally, and it is concluded that this model cannot explain catabolite repression. 4. The specific repressor hypothesis depends on the properties of a strain of E. coli carrying the CR? mutation. It requires both that cells of this genotype should be totally resistant to general catabolite repression and that this resistance should be specific for the lactose enzymes. 5. In fact the synthesis of ?-galactosidase by CR? cells, though showing resistance to catabolite repression by growth on glucose, was found to be repressed in several other circumstances. 6. Two other inducible enzymes, l-tryptophanase and d-serine deaminase, also showed resistance to repression by glucose in CR? cells. 7. It is concluded that this model, too, does not account for general catabolite repression. 8. Strains carrying deletions at either end of the lactose operon that extend into the structural genes of the operon continue to exhibit catabolite repression. 9. These experiments appear to eliminate the possibility that catabolite repression operates at the level of DNA transcription, and suggest that repression affects instead the translation of messenger RNA into protein. PMID:4881142

  15. Adherence of Escherichia coli to Human Urinary Tract Epithelial Cells

    PubMed Central

    Schaeffer, Anthony J.; Amundsen, Susan K.; Schmidt, Lawrence N.

    1979-01-01

    The adherence of Escherichia coli to human uroepithelial cells obtained from midstream urine specimens of healthy women was studied. Bacteria labeled with [3H]uridine were used, and unattached organisms were separated from the epithelial cells by vacuum filtration with 5-?m-pore-size Nucleopore membrane filters. These techniques allowed adherence to be measured in large numbers of epithelial cells and overcame the problem of distinguishing experimental bacteria from the indigenous organisms present on uroepithelial cells. Adherence was not appreciably affected by temperature. Adherence was maximal at pH 4 to 5 and at bacterial-to-epithelial-cell ratios of 5,000 or more. The latter observation suggested that there are a limited number of receptors on the epithelial cell surface, an idea which was supported by competition experiments. Adherence occurred within 1 min and then decreased gradually or quickly, depending on the type of bacterial growth medium, to a stationary level of adherence, approximately 50% of that observed initially. The ability of epithelial cells from a single individual to bind E. coli varied in a cyclical and repetitive pattern. Adherence tended to be higher during the early phase of the menstrual cycle and diminished shortly after the time of expected ovulation; adherence frequently correlated with the value obtained on the same day of the menstrual cycle during the preceding months. Adherence was markedly enhanced by bacterial incubation in broth for 72 h and inhibited by ?-d-mannose. These results suggest that adherence is a complex phenomenon perhaps mediated in part by bacterial pili and mannose residues on uroepithelial cells. PMID:38207

  16. Vascular permeability activity in Escherichia coli heat-stable enterotoxin.

    PubMed

    Craig, J P; Yamamoto, K; Takeda, T; Takeda, Y; Miwatani, T

    1981-08-01

    Purified heat-stable enterotoxin (ST) prepared from supernatants of Escherichia coli strain 53402 A-1, isolated from a patient with diarrhea, caused an increase in the permeability of the small blood vessels of the skin of adult rabbits after intracutaneous injection. Increased permeability was manifested by localized accumulation of intravenously injected blue dye at the injection sites. Permeability factor (PF) activity reached a peak 1 h after injection, and recovery of normal permeability was nearly complete in 3 h. Residual PF activity had disappeared by 24 h. Dose-response curves demonstrated a straight-line relationship between the logarithm of the dose and mean blueing diameter over a range of 3 to 12 mm. The PF assay was less sensitive that the suckling mouse assay, and adult rabbits varied in their sensitivity to the PF effect. Five to 100 mouse units of ST were required to consistently evoke strong and unequivocal blue lesions of 7 mm or more in diameter. PF activity was reduced 50 to 70% by heating at 70 degrees C for 30 min, 60 to 80% by boiling for 30 min, and 95 to 98% by autoclaving for 15 min, but it was unaffected by treatment with cholera antitoxin. These findings are consistent with the notion that PF activity is a property of the ST molecule itself. This PF assay cannot be used for the detection of ST in crude culture supernatant fluid because of low sensitivity and the presence of nonspecific PF effects of culture media and other E. coli products. PMID:7196884

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

    PubMed Central

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

    2015-01-01

    Guide RNA molecules (crRNA) produced from clustered regularly interspaced short palindromic repeat (CRISPR) arrays, altogether with effector proteins (Cas) encoded by cognate cas (CRISPR associated) genes, mount an interference mechanism (CRISPR-Cas) that limits acquisition of foreign DNA in Bacteria and Archaea. The specificity of this action is provided by the repeat intervening spacer carried in the crRNA, which upon hybridization with complementary sequences enables their degradation by a Cas endonuclease. Moreover, CRISPR arrays are dynamic landscapes that may gain new spacers from infecting elements or lose them for example during genome replication. Thus, the spacer content of a strain determines the diversity of sequences that can be targeted by the corresponding CRISPR-Cas system reflecting its functionality. Most Escherichia coli strains possess either type I-E or I-F CRISPR-Cas systems. To evaluate their impact on the pathogenicity of the species, we inferred the pathotype and pathogenic potential of 126 strains of this and other closely related species and analyzed their repeat content. Our results revealed a negative correlation between the number of I-E CRISPR units in this system and the presence of pathogenicity traits: the median number of repeats was 2.5-fold higher for commensal isolates (with 29.5 units, range 0–53) than for pathogenic ones (12.0, range 0–42). Moreover, the higher the number of virulence factors within a strain, the lower the repeat content. Additionally, pathogenic strains of distinct ecological niches (i.e., intestinal or extraintestinal) differ in repeat counts. Altogether, these findings support an evolutionary connection between CRISPR and pathogenicity in E. coli. PMID:26136211

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

    PubMed

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

    1991-10-01

    For the study of molybdenum uptake by Escherichia coli, we generated Tn5lac transposition mutants, which were screened for the pleiotropic loss of molybdoenzyme activities. Three mutants A1, A4, and M22 were finally selected for further analysis. Even in the presence of 100 microM molybdate in the growth medium, no active nitrate reductase, formate dehydrogenase, and trimethylamine-N-oxide reductase were detected in these mutants, indicating that the intracellular supply of molybdenum was not sufficient. This was also supported by the observation that introduction of plasmid pWK225 carrying the complete nif regulon of Klebsiella pneumoniae did not lead to a functional expression of nitrogenase. Finally, molybdenum determination by induced coupled plasma mass spectroscopy confirmed a significant reduction of cell-bound molybdenum in the mutants compared with that in wild-type E. coli, even at high molybdate concentrations in the medium. A genomic library established with the plasmid mini-F-derived cop(ts) vector pJE258 allowed the isolation of cosmid pBK229 complementing the molybdate uptake deficiency of the chlD mutant and the Tn5lac-induced mutants. Certain subfragments of pBK229 which do not contain the chlD gene are still able to complement the Tn5lac mutants. Mapping experiments showed that the Tn5lac insertions did not occur within the chromosomal region present in pBK229 but did occur very close to that region. We assume that the Tn5lac insertions have a polar effect, thus preventing the expression of transport genes, or that a positively acting regulatory element was inactivated. PMID:1655715

  19. Peyer's patch adherence of enteropathogenic Escherichia coli strains in rabbits.

    PubMed

    Von Moll, L K; Cantey, J R

    1997-09-01

    RDEC-1 (serotype O15) is an attaching and effacing strain of rabbit enteropathogenic Escherichia coli (REPEC) that causes diarrhea in postweanling rabbits. It expresses AF/R1 pili that mediate Peyer's patch M-cell adherence. We investigated Peyer's patch adherence, the presence of virulence genes, ileal brush border aggregation, and pilus expression in 9 strains representing several serotypes of REPEC as well as in two commensal strains. Postweanling rabbits were inoculated with 10(6) organisms and sacrificed at 24 h, and tissues were prepared for examination by light microscopy. Strains B10 and RDEC-1 were also studied at 12 and 72 h postinoculation. All REPEC strains were eaeA positive, expressed pili, and adhered to ileal brush borders. Both commensal strains expressed pili, and one strain adhered to brush borders. All REPEC strains demonstrated some degree of Peyer's patch lymphoid follicle adherence, ranging from diffuse coverage to small patches covering two to three dome epithelial cells. Strains C102 and C110 had genes homologous with the structural subunit gene of the AF/R1 pilus (afrA) of RDEC-1, which correlated with greater degrees of lymphoid follicle adherence and lesser degrees of ileal villus adherence. The observation that all REPEC strains adhere to Peyer's patch epithelium suggests the possibility that human strains of enteropathogenic E. coli (EPEC) might do likewise. EPEC strains might thus serve as mucosal vaccine vectors in humans. Better understanding of the molecular mechanism of REPEC adherence should provide a model for the targeting of the Peyer's patch in humans. PMID:9284153

  20. Occurrence of Listeria monocytogenes, Salmonella spp., Escherichia coli and E. coli O157:H7 in vegetable salads

    Microsoft Academic Search

    Chia-Min Lin; Samuel Y. Fernando; Cheng-i Wei

    1996-01-01

    The occurrence of Listeria monocytogenes, Salmonella spp., Escherichia coli and E. coli O157:H7 in 63 vegetable salads served at 31 food service facilities (four supermarkets, 14 fast food chain restaurants, and 13 family restaurants) was examined. Homogenized salad samples were incubated in half-strength TSB for 6 h, then in specific selective enrichment media for each bacterial species. After cultures were

  1. Non-O157 Shiga toxin-producing Escherichia coli associated with venison.

    PubMed

    Rounds, Joshua M; Rigdon, Carrie E; Muhl, Levi J; Forstner, Matthew; Danzeisen, Gregory T; Koziol, Bonnie S; Taylor, Charlott; Shaw, Bryanne T; Short, Ginette L; Smith, Kirk E

    2012-02-01

    We investigated an outbreak of non-O157 Shiga toxin-producing Escherichia coli at a high school in Minnesota, USA, in November 2010. Consuming undercooked venison and not washing hands after handling raw venison were associated with illness. E. coli O103:H2 and non-Shiga toxin-producing E. coli O145:NM were isolated from ill students and venison. PMID:22305114

  2. Production of d-tagatose 3-epimerase of Pseudomonas cichorii ST24 using recombinant Escherichia coli

    Microsoft Academic Search

    Yutaka Ishida; Takanori Kamiya; Ken Izumori

    1997-01-01

    The d-tagatose 3-epimerase (d-TE) gene of Pseudomonas cichorii ST-24 was expressed in Escherichia coli under the control of the trc promoter. The d-TE production level was highest in E. coli JM105 as a host strain and in NZC medium as a culture medium. Production of d-TE by E. coli JM105 was about 100-fold higher than that of d-TE by P.

  3. Antimicrobial psoriasin (S100A7) protects human skin from Escherichia coli infection

    Microsoft Academic Search

    Regine Gläser; Jürgen Harder; Hans Lange; Joachim Bartels; Enno Christophers; Jens-Michael Schröder

    2004-01-01

    Human healthy skin is continuously exposed to bacteria, but is particularly resistant to the common gut bacterium Escherichia coli. We show here that keratinocytes secrete, as the main E. coli–killing compound, the S100 protein psoriasin in vitro and in vivo in a site-dependent way. In vivo treatment of human skin with antibodies to psoriasin inhibited its E. coli–killing properties. Psoriasin

  4. Microbial production of N-acetylneuraminic acid by genetically engineered Escherichia coli

    Microsoft Academic Search

    Mari Ishikawa; Satoshi Koizumi

    2010-01-01

    Previously, we described the production of N-acetylneuraminic acid (NeuAc) from N-acetylglucosamine (GlcNAc) in a system combining recombinant Escherichia coli expressing GlcNAc 2-epimerase (slr1975), E. coli expressing NeuAc synthetase (neuB), and Corynebacterium ammoniagenes. However, this system was unsuitable for large-scale production because of its complexity and low productivity. To overcome these problems, we constructed a recombinant E. coli simultaneously overexpressing slr1975

  5. Gold screen-printed-based impedimetric immunobiosensors for direct and sensitive Escherichia coli quantisation

    Microsoft Academic Search

    Vanessa Escamilla-Gómez; Susana Campuzano; María Pedrero; José M. Pingarrón

    2009-01-01

    Label-free electrochemical impedance immunosensors for the detection and quantification of Escherichia coli (E. coli) using self-assembled monolayers (SAMs)-modified gold screen-printed electrodes (AuSPEs) were developed. Two different immunosensor configurations were tested and compared. In the first one, the immunosensing design was based on the covalent immobilization of anti-E. coli at AuSPEs using the homobifunctional cross-linker 3,3?-dithiobis[sulfosuccinimidylpropionate] (DTSSP). The other one was

  6. Antimicrobial Resistance of Escherichia coli Strains Causing Neonatal Sepsis between 1998 and 2008

    Microsoft Academic Search

    Elisabet Guiral; Jordi Bosch; Jordi Vila; Sara M. Soto

    2012-01-01

    Background: Bloodstream infections are a significant cause of neonatal morbidity and death. An increase in the incidence of early neonatal sepsis due to Escherichia coli has been reported. The objective was to evaluate the antimicrobial resistance of E. coli strains causing early-onset neonatal sepsis (EONS) and late-onset neonatal sepsis (LONS) and their evolution. Methods:E. coli strains from EONS and hospital-acquired

  7. SYMPOSIUM: FARM HEALTH AND SAFETY Invited Review: Effects of Diet Shifts on Escherichia coli in Cattle

    Microsoft Academic Search

    J. B. Russell; F. Diez-Gonzalez; G. N. Jarvis

    Escherichia coli O157:H7 is a pathogenic bacterium that causes acute illness in humans, but mature cattle are not affected. E. coli O157:H7 can enter the human food supply from cattle via fecal contamination of beef carcasses at slaughter. Previous attempts to correlate the incidence of E. coli O157:H7 with specific diets or feeding management practices gave few statistically significant or

  8. Membrane-derived oligosaccharides (MDOs) are essential for sodium dodecyl sulfate resistance in Escherichia coli

    Microsoft Academic Search

    Soumitra Rajagopal; Nicole Eis; Meenakshi Bhattacharya; Kenneth W Nickerson

    2003-01-01

    We studied the role of membrane-derived oligosaccharides (MDOs) in sodium dodecyl sulfate (SDS) resistance by Escherichia coli. MDOs are also known as osmoregulated periplasmic glucans. Wild-type E. coli MC4100 grew in the presence of 10% SDS whereas isogenic mdoA and mdoB mutants could not grow above 0.5% SDS. Similarly, E. coli DF214, a mutant (pgi, zwf) unable to grow on

  9. Recovery of Escherichia coli ATCC 25922 in phosphate buffered saline after treatment with high hydrostatic pressure

    Microsoft Academic Search

    Shigenobu Koseki; Kazutaka Yamamoto

    2006-01-01

    Escherichia coli ATCC 25922 in phosphate buffered saline solution (PBS, pH 7.1, 108 CFU\\/ml) was inactivated by high hydrostatic pressure (HHP, 400 to 600 MPa) treatment at 25 °C for 10 min. Colonies of E. coli were not detected on non-selective plate count agar immediately after a HHP-treatment of at least 550 MPa. E. coli subjected to at least 500 MPa in PBS were incubated at

  10. Multiple sources of Escherichia coli O157 in feedlots and dairy farms in the Northwestern USA

    Microsoft Academic Search

    Dale D Hancock; Thomas E Besser; Daniel H Rice; Eric D Ebel; Donald E Herriott; Linda V Carpenter

    1998-01-01

    Samples from cattle, other domestic and wild animals, flies, feeds, and water-troughs were collected from 12 cattle farms and tested for Escherichia coli O157. E. coli O157 was isolated from bovine fecal samples on all 12 farms with a within herd prevalence ranging from 1.1% to 6.1%. E. coli O157 was also found in 1 of 90 (1.1%) equine fecal

  11. Genomics, Biological Features, and Biotechnological Applications of Escherichia coli B: “Is B for better?!”

    Microsoft Academic Search

    Sung Ho Yoon; Haeyoung Jeong; Soon-Kyeong Kwon; Jihyun F. Kim

    Strains of Escherichia coli B, especially BL21, have been widely used for overproducing recombinant proteins, ethanol, and other biomolecules. Almost\\u000a all laboratory strains of E. coli are derivatives of non-pathogenic K-12 or B strains. While most genetic and metabolic studies have been performed with K-12\\u000a strains, little has been done on B strains. Recently, genome sequences of two E. coli

  12. Investigating the Mechanisms of Ribonucleotide Excision Repair in Escherichia coli

    PubMed Central

    Vaisman, Alexandra; McDonald, John P.; Noll, Stephan; Huston, Donald; Loeb, Gregory; Goodman, Myron F.; Woodgate, Roger

    2014-01-01

    Low fidelity Escherichia coli DNA polymerase V (pol V/UmuD?2C) is best characterized for its ability to perform translesion synthesis (TLS). However, in recA730 lexA(Def) strains, the enzyme is expressed under optimal conditions allowing it to compete with the cell’s replicase for access to undamaged chromosomal DNA and leads to a substantial increase in spontaneous mutagenesis. We have recently shown that a Y11A substitution in the “steric gate” residue of UmuC reduces both base and sugar selectivity of pol V, but instead of generating an increased number of spontaneous mutations, strains expressing umuC_Y11A are poorly mutable in vivo. This phenotype is attributed to efficient RNase HII-initiated repair of the misincorporated ribonucleotides that concomitantly removes adjacent misincorporated deoxyribonucleotides. We have utilized the ability of the pol V steric gate mutant to promote incorporation of large numbers of errant ribonucleotides into the E. coli genome to investigate the fundamental mechanisms underlying ribonucleotide excision repair (RER). Here, we demonstrate that RER is normally facilitated by DNA polymerase I (pol I) via classical “nick translation”. In vitro, pol I displaces 1–3 nucleotides of the RNA/DNA hybrid and through its 5??3? (exo/endo) nuclease activity releases ribo- and deoxyribonucleotides from DNA. In vivo, umuC_Y11A-dependent mutagenesis changes significantly in polymerase-deficient, or proofreading-deficient polA strains, indicating a pivotal role for pol I in ribonucleotide excision repair (RER). However, there is also considerable redundancy in the RER pathway in E. coli. Pol I’s strand displacement and FLAP- exo/endonuclease activities can be facilitated by alternate enzymes, while the DNA polymerization step can be assumed by high-fidelity pol III. We conclude that RNase HII and pol I normally act to minimize the genomic instability that is generated through errant ribonucleotide incorporation, but that the “nick-translation” activities encoded by the single pol I polypeptide can be undertaken by a variety of back-up enzymes. PMID:24495324

  13. Production of extracellular fatty acid using engineered Escherichia coli

    PubMed Central

    2012-01-01

    Background As an alternative for economic biodiesel production, the microbial production of extracellular fatty acid from renewable resources is receiving more concerns recently, since the separation of fatty acid from microorganism cells is normally involved in a series of energy-intensive steps. Many attempts have been made to construct fatty acid producing strains by targeting genes in the fatty acid biosynthetic pathway, while few studies focused on the cultivation process and the mass transfer kinetics. Results In this study, both strain improvements and cultivation process strategies were applied to increase extracellular fatty acid production by engineered Escherichia coli. Our results showed overexpressing ‘TesA and the deletion of fadL in E. coli BL21 (DE3) improved extracellular fatty acid production, while deletion of fadD didn’t strengthen the extracellular fatty acid production for an undetermined mechanism. Moreover, the cultivation process controls contributed greatly to extracellular fatty acid production with respect to titer, cell growth and productivity by adjusting the temperature, adding ampicillin and employing on-line extraction. Under optimal conditions, the E. coli strain (pACY-‘tesA-?fadL) produced 4.8 g?L?1 extracellular fatty acid, with the specific productivity of 0.02 g?h?1 g?1dry cell mass, and the yield of 4.4% on glucose, while the ratios of cell-associated fatty acid versus extracellular fatty acid were kept below 0.5 after 15 h of cultivation. The fatty acids included C12:1, C12:0, C14:1, C14:0, C16:1, C16:0, C18:1, C18:0. The composition was dominated by C14 and C16 saturated and unsaturated fatty acids. Using the strain pACY-‘tesA, similar results appeared under the same culture conditions and the titer was also much higher than that ever reported previously, which suggested that the supposedly superior strain did not necessarily perform best for the efficient production of desired product. The strain pACY-‘tesA could also be chosen as the original strain for the next genetic manipulations. Conclusions The general strategy of metabolic engineering for the extracellular fatty acid production should be the cyclic optimization between cultivation performance and strain improvements. On the basis of our cultivation process optimization, strain improvements should be further carried out for the effective and cost-effective production process. PMID:22471973

  14. Overexpression of Peanut Diacylglycerol Acyltransferase 2 in Escherichia coli

    PubMed Central

    Yang, Lianqun; Zhang, Bin; Chen, Gao; Bi, Yuping

    2013-01-01

    Diacylglycerol acyltransferase (DGAT) is the rate-limiting enzyme in triacylglycerol biosynthesis in eukaryotic organisms. Triacylglycerols are important energy-storage oils in plants such as peanuts, soybeans and rape. In this study, Arachis hypogaea type 2 DGAT (AhDGAT2) genes were cloned from the peanut cultivar ‘Luhua 14’ using a homologous gene sequence method and rapid amplification of cDNA ends. To understand the role of AhDGAT2 in triacylglycerol biosynthesis, two AhDGAT2 nucleotide sequences that differed by three amino acids were expressed as glutathione S-transferase (GST) fusion proteins in Escherichia coli Rosetta (DE3). Following IPTG induction, the isozymes (AhDGAT2a and AhDGAT2b) were expressed as 64.5 kDa GST fusion proteins. Both AhDGAT2a and AhDGAT2b occurred in the host cell cytoplasm and inclusion bodies, with larger amounts in the inclusion bodies. Overexpression of AhDGATs depressed the host cell growth rates relative to non-transformed cells, but cells harboring empty-vector, AhDGAT2a–GST, or AhDGAT2b–GST exhibited no obvious growth rate differences. Interestingly, induction of AhDGAT2a–GST and AhDGAT2b–GST proteins increased the sizes of the host cells by 2.4–2.5 times that of the controls (post-IPTG induction). The total fatty acid (FA) levels of the AhDGAT2a–GST and AhDGAT2a–GST transformants, as well as levels of C12:0, C14:0, C16:0, C16:1, C18:1n9c and C18:3n3 FAs, increased markedly, whereas C15:0 and C21:0 levels were lower than in non-transformed cells or those containing empty-vectors. In addition, the levels of some FAs differed between the two transformant strains, indicating that the two isozymes might have different functions in peanuts. This is the first time that a full-length recombinant peanut DGAT2 has been produced in a bacterial expression system and the first analysis of its effects on the content and composition of fatty acids in E. coli. Our results indicate that AhDGAT2 is a strong candidate gene for efficient FA production in E. coli. PMID:23593473

  15. Chromosomal replication incompatibility in Dam methyltransferase deficient Escherichia coli cells.

    PubMed Central

    Løbner-Olesen, A; von Freiesleben, U

    1996-01-01

    Dam methyltransferase deficient Escherichia coli cells containing minichromosomes were constructed. Free plasmid DNA could not be detected in these cells and the minichromosomes were found to be integrated in multiple copies in the origin of replication (oriC) region of the host chromosome. The absence of the initiation cascade in Dam- cells is proposed to account for this observation of apparent incompatibility between plasmid and chromosomal copies of oriC. Studies using oriC-pBR322 chimeric plasmids and their deletion derivatives indicated that the incompatibility determinant is an intact and functional oriC sequence. The seqA2 mutation was found to overcome the incompatability phenotype by increasing the cellular oriC copy number 3-fold thereby allowing minichromosomes to coexist with the chromosome. The replication pattern of a wild-type strain with multiple integrated minichromosomes in the oriC region of the chromosome, led to the conclusion that initiation of DNA replication commences at a fixed cell mass, irrespective of the number of origins contained on the chromosome. Images PMID:8918477

  16. A novel oligoribonuclease of Escherichia coli. II. Mechanism of action.

    PubMed

    Datta, A K; Niyogi, K

    1975-09-25

    Detailed studies of the mechanism of action of the novel oligoribonuclease of Escherichia coli described in the previous paper (1) led to the following conclusions. 1. The enzyme prefers a free 3'-hydroxyl group for its action. 2. The enzyme attacks the oligoribonucleotide substrate in a sequential manner from the 3' end producing 5'-ribonucleotides. 3. The mode of attack appears to be processive; the enzyme acts by degrading one oligoribonucleotide chain to completion before proceeding to the hydrolysis of another chain. 4. The reaction rate is inversely proportional to the chain length of the substrate; however, the enzyme has a higher affinity for longer chains. 5. The enzyme activity is markedly inhibited by secondary structure; oligoribonucleotides combined with complementary polyribonucleotides are attacked poorly below the melting temperature of the complex and efficiently above the melting temperature. 6. The enzyme is inhibited by 5'-nucleotides of adenine and guanine; those of cytosine and uracil have a much smaller effect. The enzyme is not inhibited by 3'-nucleotides. 7. Studies with dinucleoside monophosphate show highest reaction rates with pyrimidine sequences in the order: CpCgreater than UpUgreater than CpUgreater than UpC. The presence of guanine at the 3' end is strongly inhibitory, and reaction rates are CpGgreater than UpG=ApGgreater than GpG. PMID:170260

  17. Escherichia coli mutants resistant to inactivation by high hydrostatic pressure.

    PubMed Central

    Hauben, K J; Bartlett, D H; Soontjens, C C; Cornelis, K; Wuytack, E Y; Michiels, C W

    1997-01-01

    Alternating cycles of exposure to high pressure and outgrowth of surviving populations were used to select for highly pressure-resistant mutants of Escherichia coli MG1655. Three barotolerant mutants (LMM1010, LMM1020, and LMM1030) were isolated independently by using outgrowth temperatures of 30, 37, and 42 degrees C, respectively. Survival of these mutants after pressure treatment for 15 min at ambient temperature was 40 to 85% at 220 MPa and 0.5 to 1.5% at 800 MPa, while survival of the parent strain, MG1655, decreased from 15% at 220 MPa to 2 x 10(-8)% at 700 MPa. Heat resistance of mutants LMM1020 and LMM1030 was also altered, as evident by higher D values at 58 and 60 degrees C and reduced z values compared to those for the parent strain. D and z values for mutant LMM1010 were not significantly different from those for the parent strain. Pressure sensitivity of the mutants increased from 10 to 50 degrees C, as opposed to the parent strain, which showed a minimum around 40 degrees C. The ability of the mutants to grow at moderately elevated pressure (50 MPa) was reduced at temperatures above 37 degrees C, indicating that resistance to pressure inactivation is unrelated to barotolerant growth. The development of high levels of barotolerance as demonstrated in this work should cause concern about the safety of high-pressure food processing. PMID:9055412

  18. Mutant MotB proteins in Escherichia coli.

    PubMed

    Blair, D F; Kim, D Y; Berg, H C

    1991-07-01

    The MotB protein of Escherichia coli is an essential component in each of eight torque generators in the flagellar rotary motor. Based on its membrane topology, it has been suggested that MotB might be a linker that fastens the torque-generating machinery to the cell wall. Here, we report the isolation and characterization of a number of motB mutants. As found previously for motA, many alleles of motB were dominant, as expected if MotB is a component of the motor. In other respects, however, the motB mutants differed from the motA mutants. Most of the mutations mapped to a hydrophilic, periplasmic domain of the protein, and nothing comparable to the slow-swimming alleles of motA, which show normal torque when tethered, was found. Some motB mutants retained partial function, but when tethered they produced subnormal torque, indicating that their motors contained only one or two functional torque generators. These results support the hypothesis that MotB is a linker. PMID:2061285

  19. Oxidative stress responses in Escherichia coli and Salmonella typhimurium.

    PubMed Central

    Farr, S B; Kogoma, T

    1991-01-01

    Oxidative stress is strongly implicated in a number of diseases, such as rheumatoid arthritis, inflammatory bowel disorders, and atherosclerosis, and its emerging as one of the most important causative agents of mutagenesis, tumorigenesis, and aging. Recent progress on the genetics and molecular biology of the cellular responses to oxidative stress, primarily in Escherichia coli and Salmonella typhimurium, is summarized. Bacteria respond to oxidative stress by invoking two distinct stress responses, the peroxide stimulon and the superoxide stimulon, depending on whether the stress is mediated by peroxides or the superoxide anion. The two stimulons each contain a set of more than 30 genes. The expression of a subset of genes in each stimulon is under the control of a positive regulatory element; these genes constitute the OxyR and SoxRS regulons. The schemes of regulation of the two regulons by their respective regulators are reviewed in detail, and the overlaps of these regulons with other stress responses such as the heat shock and SOS responses are discussed. The products of Oxy-R- and SoxRS-regulated genes, such as catalases and superoxide dismutases, are involved in the prevention of oxidative damage, whereas others, such as endonuclease IV, play a role in the repair of oxidative damage. The potential roles of these and other gene products in the defense against oxidative damage in DNA, proteins, and membranes are discussed in detail. A brief discussion of the similarities and differences between oxidative stress responses in bacteria and eukaryotic organisms concludes this review. PMID:1779927

  20. The unstructured domain of colicin N kills Escherichia coli

    PubMed Central

    Johnson, Christopher L; Ridley, Helen; Pengelly, Robert J; Salleh, Mohd Zulkifli; Lakey, Jeremy H

    2013-01-01

    Bacteria often produce toxins which kill competing bacteria. Colicins, produced by and toxic to Escherichia coli bacteria are three-domain proteins so efficient that one molecule can kill a cell. The C-terminal domain carries the lethal activity and the central domain is required for surface receptor binding. The N-terminal domain, required for translocation across the outer membrane, is always intrinsically unstructured. It has always been assumed therefore that the C-terminal cytotoxic domain is required for the bactericidal activity. Here we report the unexpected finding that in isolation, the 90-residue unstructured N-terminal domain of colicin N is cytotoxic. Furthermore it causes ion leakage from cells but, unlike known antimicrobial peptides (AMPs) with this property, shows no membrane binding behaviour. Finally, its activity remains strictly dependent upon the same receptor proteins (OmpF and TolA) used by full-length colicin N. This mechanism of rapid membrane disruption, via receptor mediated binding of a soluble peptide, may reveal a new target for the development of highly specific antibacterials. PMID:23672584

  1. Bundle-forming pilus retraction enhances enteropathogenic Escherichia coli infectivity

    PubMed Central

    Zahavi, Eitan E.; Lieberman, Joshua A.; Donnenberg, Michael S.; Nitzan, Mor; Baruch, Kobi; Rosenshine, Ilan; Turner, Jerrold R.; Melamed-Book, Naomi; Feinstein, Naomi; Zlotkin-Rivkin, Efrat; Aroeti, Benjamin

    2011-01-01

    Enteropathogenic Escherichia coli (EPEC) is an important human pathogen that causes acute infantile diarrhea. The type IV bundle-forming pili (BFP) of typical EPEC strains are dynamic fibrillar organelles that can extend out and retract into the bacterium. The bfpF gene encodes for BfpF, a protein that promotes pili retraction. The BFP are involved in bacterial autoaggregation and in mediating the initial adherence of the bacterium with its host cell. Importantly, BFP retraction is implicated in virulence in experimental human infection. How pili retraction contributes to EPEC pathogenesis at the cellular level remains largely obscure, however. In this study, an effort has been made to address this question using engineered EPEC strains with induced BFP retraction capacity. We show that the retraction is important for tight-junction disruption and, to a lesser extent, actin-rich pedestal formation by promoting efficient translocation of bacterial protein effectors into the host cells. A model is proposed whereby BFP retraction permits closer apposition between the bacterial and the host cell surfaces, thus enabling timely and effective introduction of bacterial effectors into the host cell via the type III secretion apparatus. Our studies hence suggest novel insights into the involvement of pili retraction in EPEC pathogenesis. PMID:21613538

  2. Adherent-invasive Escherichia coli target the epithelial barrier

    PubMed Central

    Ossa, Juan C; Gray-Owen, Scott D; Sherman, Philip M

    2010-01-01

    Involvement of intestinal microbes in the pathogenesis of chronic inflammatory bowel diseases (IBD, including Crohn disease and ulcerative colitis) is well established. However, the mechanisms by which bacteria lead to intestinal injury in IBD remain unclear and are the focus of current research. Using adherent-invasive Escherichia coli (AIEC) strain LF82, which is linked to Crohn disease, we recently demonstrated the ability of these intestinal microbes to disrupt the integrity of epithelial cells in an in vitro cell model. This disruption provides the bacteria a capacity to penetrate into and beyond the epithelial monolayer, replicate in cells, disseminate within the host, and induce a chronic immune response. These findings provide a link between microbes related to IBD, disruption of the intestinal epithelial cell barrier, and disease pathogenesis. In this addendum, we provide a synopsis on current data concerning the role of AIEC in the pathogenesis of intestinal inflammation, summarise our recent findings, and highlight the central role of the epithelium in mucosal defence. We also discuss, in more detail, the potential implications of our findings and present ideas for future studies and targets for intervention. PMID:21326914

  3. A Comparison of Methods to Measure Fitness in Escherichia coli

    PubMed Central

    Wiser, Michael J.; Lenski, Richard E.

    2015-01-01

    In order to characterize the dynamics of adaptation, it is important to be able to quantify how a population’s mean fitness changes over time. Such measurements are especially important in experimental studies of evolution using microbes. The Long-Term Evolution Experiment (LTEE) with Escherichia coli provides one such system in which mean fitness has been measured by competing derived and ancestral populations. The traditional method used to measure fitness in the LTEE and many similar experiments, though, is subject to a potential limitation. As the relative fitness of the two competitors diverges, the measurement error increases because the less-fit population becomes increasingly small and cannot be enumerated as precisely. Here, we present and employ two alternatives to the traditional method. One is based on reducing the fitness differential between the competitors by using a common reference competitor from an intermediate generation that has intermediate fitness; the other alternative increases the initial population size of the less-fit, ancestral competitor. We performed a total of 480 competitions to compare the statistical properties of estimates obtained using these alternative methods with those obtained using the traditional method for samples taken over 50,000 generations from one of the LTEE populations. On balance, neither alternative method yielded measurements that were more precise than the traditional method. PMID:25961572

  4. Photoluminescent Gold Nanoclusters as Sensing Probes for Uropathogenic Escherichia coli

    PubMed Central

    Lai, Hong-Zheng; Peng, Hwei-Ling; Mong, Kwok Kong Tony; Chen, Yu-Chie

    2013-01-01

    Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs). The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann) were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH) was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.95±0.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ?630 nm (?excitation?=?375 nm). The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ?2×106 cells/mL. PMID:23554874

  5. Proteolytic Activity of YibP Protein in Escherichia coli

    PubMed Central

    Ichimura, Toshiharu; Yamazoe, Mitsuyoshi; Maeda, Maki; Wada, Chieko; Hiraga, Sota

    2002-01-01

    Escherichia coli YibP protein (47.4 kDa) has a membrane-spanning signal at the N-terminal region, two long coiled-coil regions in the middle part, and a C-terminal globular domain, which involves amino acid sequences homologous to the peptidase M23/M37 family. A yibP disrupted mutant grows in rich medium at 37°C but not at 42°C. In the yibP null mutant, cell division and FtsZ ring formation are inhibited at 42°C without SOS induction, resulting in filamentous cells with multiple nucleoids and finally in cell lysis. Five percent betaine suppresses the temperature sensitivity of the yibP disrupted mutation. The mutant has the same sensitivity to drugs, such as nalidixic acid, ethidium bromide, ethylmethane sulfonate, and sodium dodecyl sulfate, as the parental strain. YibP protein is recovered in the inner membrane and cytoplasmic fractions, but not in the outer membrane fraction. Results suggest that the coiled-coil regions and the C-terminal globular domain of YibP are localized in the cytoplasmic space, not in the periplasmic space. Purified YibP has a protease activity that split the substrate ?-casein. PMID:11976287

  6. Purification of a rat neurotensin receptor expressed in Escherichia coli.

    PubMed Central

    Tucker, J; Grisshammer, R

    1996-01-01

    A truncated rat neurotensin receptor (NTR), expressed in Escherichia coli with the maltose-binding protein fused to its N-terminus and the 13 amino acid Bio tag fused to its C-terminus, was purified to apparent homogeneity in two steps by use of the monomeric avidin system followed by a novel neurotensin column. This purification protocol was developed by engineering a variety of affinity tags on to the C-terminus of NTR. Surprisingly, expression levels varied considerably depending on the C-terminal tag used. Functional expression of NTR was highest (800 receptors/cell) when thioredoxin was placed between the receptor C-terminus and the tag, indicating a stabilizing effect of the thioredoxin moiety. Several affinity chromatography methods were tested for purification. NTR with the in vivo-biotinylated Bio tag was purified with the highest efficiency compared with NTR with the Strep tag or a hexa-histidine tail. Co-expression of biotin ligase improved considerably the in vivo biotinylation of the Bio tag and, therefore, the overall purification yield. Proteolysis of the NTR fusion protein was prevented by removing a protease-sensitive site discovered at the N-terminus of NTR. The ligand binding properties of the purified receptor were similar to those of the membrane-bound protein and the native receptor. The scale-up of this purification scheme, to provide sufficient protein for biophysical studies, is in progress. PMID:8760379

  7. Monoclonal antibodies to Escherichia coli 50S ribosomes.

    PubMed Central

    Shen, V; King, T C; Kumar, V; Daugherty, B

    1980-01-01

    Hybridoma cell lines that produce monoclonal antibodies directed against 50S Ribosomal proteins have been isolated. Spleen cells (from BALB/c mice immunized with 50S ribosomal subunits extracted from Escherichia coli) were fused to mouse myeloma cell line SP2/O-Ag 14. The initial screening for antibody producing hybridomas was carried out by a double antibody sandwich method; hybridomas were subsequently cloned in soft agar. Antibodies were characterized by their specific binding to individual 50S ribsomal proteins separated on phosphocellulose columns and in two-dimensional polyacrylamide gels. The assignments were confirmed with purified single ribosomal proteins. Of four clones analyzed thus far, two are identical with specificity for r-protein L5. The other clones produce two different antibodies directed against r-protein L20. Each monoclonal antibody formed ribosome dimers visualizable in the electron microscope. Dimers could be reacted with a different second antibody to form chains containing 8 or more ribosomes, which may be useful for structural studies. Images PMID:6160475

  8. Switchable Gene Expression in Escherichia coli Using a Miniaturized Photobioreactor

    PubMed Central

    Kim, Taesung; Lee, Sung Kuk

    2013-01-01

    We present a light-switchable gene expression system for both inducible and switchable control of gene expression at a single cell level in Escherichia coli using a previously constructed light-sensing system. The ? cI repressor gene with an LVA degradation tag was expressed under the control of the ompC promoter on the chromosome. The green fluorescent protein (GFP) gene fused to a ? repressor-repressible promoter was used as a reporter. This light-switchable system allows rapid and reversible induction or repression of expression of the target gene at any desired time. This system also ensures homogenous expression across the entire cell population. We also report the design of a miniaturized photobioreactor to be used in combination with the light-switchable gene expression system. The miniaturized photobioreactor helps to reduce unintended induction of the light receptor due to environmental disturbances and allows precise control over the duration of induction. This system would be a good tool for switchable, homogenous, strong, and highly regulatable expression of target genes over a wide range of induction times. Hence, it could be applied to study gene function, optimize metabolic pathways, and control biological systems both spatially and temporally. PMID:23349683

  9. Identification of the ferroxidase centre of Escherichia coli bacterioferritin.

    PubMed

    Le Brun, N E; Andrews, S C; Guest, J R; Harrison, P M; Moore, G R; Thomson, A J

    1995-12-01

    The bacterioferritin (BFR) of Escherichia coli takes up iron in the ferrous form and stores it within its central cavity as a hydrated ferric oxide mineral. The mechanism by which oxidation of iron (II) occurs in BFR is largely unknown, but previous studies indicated that there is ferroxidase activity associated with a site capable of forming a dinuclear-iron centre within each subunit [Le Brun, Wilson, Andrews, Harrison, Guest, Thomson and Moore (1993) FEBS Lett. 333, 197-202]. We now report site-directed mutagenesis experiments based on a putative dinuclear-metal-ion-binding site located within the BFR subunit. The data reveal that this dinuclear-iron centre is located at a site within the four-alpha-helical bundle of each subunit of BFR, thus identified as the ferroxidase centre of BFR. The metal-bound form of the centre bears a remarkable similarity to the dinuclear-iron sites of the hydroxylase subunit of methane mono-oxygenase and the R2 subunit of ribonucleotide reductase. Details of how the dinuclear centre of BFR is involved in the oxidation mechanism were investigated by studying the inhibition of iron (II) oxidation by zinc (II) ions. Data indicate that zinc (II) ions bind at the ferroxidase centre of apo-BFR in preference to iron (II), resulting in a dramatic reduction in the rate of oxidation. The mechanism of iron (II) oxidation is discussed in the light of this and previous work. PMID:8526846

  10. Release of Compact Nucleoids with Characteristic Shapes from Escherichia coli

    PubMed Central

    Zimmerman, Steven B.; Murphy, Lizabeth D.

    2001-01-01

    The genomic DNA of bacteria is contained in one or a few compact bodies known as nucleoids. We describe a simple procedure that retains the general shape and compaction of nucleoids from Escherichia coli upon cell lysis and nucleoid release from the cell envelope. The procedure is a modification of that used for the preparation of spermidine nucleoids (nucleoids released in the presence of spermidine) (T. Kornberg, A. Lockwood, and A. Worcel, Proc. Natl. Acad. Sci. USA 71:3189–3193, 1974). Polylysine is added to prevent the normal decompaction of nucleoids which occurs upon cell lysis. Nucleoids retained their characteristic shapes in lysates of exponential-phase cells or in lysates of cells treated with chloramphenicol or nalidixate to alter nucleoid morphology. The notably unstable nucleoids of rifampin-treated cells were obtained in compact, stable form in such lysates. Nucleoids released in the presence of polylysine were easily processed and provided well-defined DNA fluorescence and phase-contrast images. Uniform populations of nucleoids retaining characteristic shapes could be isolated after formaldehyde fixation and heating with sodium dodecyl sulfate. PMID:11489856

  11. Metabolic engineering of anthocyanin biosynthesis in Escherichia coli.

    PubMed

    Yan, Yajun; Chemler, Joseph; Huang, Lixuan; Martens, Stefan; Koffas, Mattheos A G

    2005-07-01

    Anthocyanins are red, purple, or blue plant pigments that belong to the family of polyphenolic compounds collectively called flavonoids. Their demonstrated antioxidant properties and economic importance to the dye, fruit, and cut-flower industries have driven intensive research into their metabolic biosynthetic pathways. In order to produce stable, glycosylated anthocyanins from colorless flavanones such as naringenin and eriodictyol, a four-step metabolic pathway was constructed that contained plant genes from heterologous origins: flavanone 3beta-hydroxylase from Malus domestica, dihydroflavonol 4-reductase from Anthurium andraeanum, anthocyanidin synthase (ANS) also from M. domestica, and UDP-glucose:flavonoid 3-O-glucosyltransferase from Petunia hybrida. Using two rounds of PCR, each one of the four genes was first placed under the control of the trc promoter and its own bacterial ribosome-binding site and then cloned sequentially into vector pK184. Escherichia coli cells containing the recombinant plant pathway were able to take up either naringenin or eriodictyol and convert it to the corresponding glycosylated anthocyanin, pelargonidin 3-O-glucoside or cyanidin 3-O-glucoside. The produced anthocyanins were present at low concentrations, while most of the metabolites detected corresponded to their dihydroflavonol precursors, as well as the corresponding flavonols. The presence of side product flavonols is at least partly due to an alternate reaction catalyzed by ANS. This is the first time plant-specific anthocyanins have been produced from a microorganism and opens up the possibility of further production improvement by protein and pathway engineering. PMID:16000769

  12. Determination of active site residues in Escherichia coli endonuclease VIII.

    PubMed

    Burgess, Sarah; Jaruga, Pawel; Dodson, M L; Dizdaroglu, Miral; Lloyd, R Stephen

    2002-01-25

    Endonuclease VIII from Escherichia coli is a DNA glycosylase/lyase that removes oxidatively damaged bases. EndoVIII is a functional homologue of endonuclease III, but a sequence homologue of formamidopyrimidine-DNA glycosylase (Fpg). Using multiple sequence alignments, we have identified six target residues in endoVIII that may be involved in the enzyme's glycosylase and/or lyase functions: the N-terminal proline, and five acidic residues that are completely conserved in the endoVIII-Fpg proteins. To investigate the contribution of these residues, site-directed mutagenesis was used to create seven mutants: P2T, E3D, E3Q, E6Q, D129N, D160N, and E174Q. Each mutant was assayed both for lyase activity on abasic (AP) sites and for glycosylase/lyase activity on 5-hydroxyuracil, thymine glycol, and gamma-irradiated DNA with multiple lesions. The P2T mutant did not have lyase or glycosylase/lyase activity but could efficiently form Schiff base intermediates on AP sites. E6Q, D129N, and D160N behaved essentially as endoVIII in all assays. E3D, E3Q, and E174Q retained significant AP lyase activity but had severely diminished or abolished glycosylase/lyase activities on the DNA lesions tested. These studies provide detailed predictions concerning the active site of endoVIII. PMID:11711552

  13. Evolution of diversity in spatially structured Escherichia coli populations.

    PubMed

    Ponciano, José Miguel; La, Hyun-Joon; Joyce, Paul; Forney, Larry J

    2009-10-01

    The stochastic Ricker population model was used to investigate the generation and maintenance of genetic diversity in a bacterial population grown in a spatially structured environment. In particular, we showed that Escherichia coli undergoes dramatic genetic diversification when grown as a biofilm. Using a novel biofilm entrapment method, we retrieved 64 clones from each of six different depths of a mature biofilm, and after subculturing for approximately 30 generations, we measured their growth kinetics in three different media. We fit a stochastic Ricker population growth model to the recorded growth curves. The growth kinetics of clonal lineages descendant from cells sampled at different biofilm depths varied as a function of both the depth in the biofilm and the growth medium used. We concluded that differences in the growth dynamics of clones were heritable and arose during adaptive evolution under local conditions in a spatially heterogeneous environment. We postulate that under nutrient-limited conditions, selective sweeps would be protracted and would be insufficient to purge less-fit variants, a phenomenon that would allow the coexistence of genetically distinct clones. These findings contribute to the current understanding of biofilm ecology and complement current hypotheses for the maintenance and generation of microbial diversity in spatially structured environments. PMID:19648364

  14. Torque generated by the flagellar motor of Escherichia coli.

    PubMed Central

    Berg, H C; Turner, L

    1993-01-01

    Cells of the bacterium Escherichia coli were tethered and spun in a high-frequency rotating electric field at a series of discrete field strengths. This was done first at low field strengths, then at field strengths generating speeds high enough to disrupt motor function, and finally at low field strengths. Comparison of the initial and final speed versus applied-torque plots yielded relative motor torque. For backward rotation, motor torque rose steeply at speeds close to zero, peaking, on average, at about 2.2 times the stall torque. For forward rotation, motor torque remained approximately constant up to speeds of about 60% of the zero-torque speed. Then the torque dropped linearly with speed, crossed zero, and reached a minimum, on average, at about -1.7 times the stall torque. The zero-torque speed increased with temperature (about 90 Hz at 11 degrees C, 140 Hz at 16 degrees C, and 290 Hz at 23 degrees C), while other parameters remained approximately constant. Sometimes the motor slipped at either extreme (delivered constant torque over a range of speeds), but eventually it broke. Similar results were obtained whether motors broke catastrophically (suddenly and completely) or progressively or were de-energized by brief treatment with an uncoupler. These results are consistent with a tightly coupled ratchet mechanism, provided that elastic deformation of force-generating elements is limited by a stop and that mechanical components yield at high applied torques. PMID:8298044

  15. Bovine macrophages sense Escherichia coli Shiga toxin 1.

    PubMed

    Menge, Christian; Loos, Daniela; Bridger, Philip S; Barth, Stefanie; Werling, Dirk; Baljer, Georg

    2015-08-01

    Shiga toxin (Stx)-producing Escherichia coli (STEC) infections in cattle are asymptomatic; however, Stx impairs the initiation of an adaptive immune response by targeting bovine peripheral and intraepithelial lymphocytes. As presumptive bovine mucosal macrophages (Mø) are also sensitive to Stx, STEC may even exert immune modulatory effects by acting on steps preceding lymphocyte activation at the Mø level. We therefore studied the expression of the Stx receptor (CD77), cellular phenotype and functions after incubation of primary bovine monocyte-derived Mø with purified Stx1. A significant portion of bovine Mø expressed CD77 on their surface, with the recombinant B-subunit of Stx1 binding to >50% of the cells. Stx1 down-regulated significantly surface expression of CD14, CD172a and co-stimulatory molecules CD80 and CD86 within 4?h of incubation, while MHC-II expression remained unaffected. Furthermore, incubation of Mø with Stx1 increased significantly numbers of transcripts for IL-4, IL-6, IL-10, IFN-?, TNF-?, IL-8 and GRO-? but not for IL-12, TGF-?, MCP-1 and RANTES. In the course of bovine STEC infections, Stx1 appears to induce in Mø a mixed response pattern reminiscent of regulatory Mø, which may amplify the direct suppressive effect of the toxin on lymphocytes. PMID:25907071

  16. Control site location and transcriptional regulation in Escherichia coli.

    PubMed Central

    Collado-Vides, J; Magasanik, B; Gralla, J D

    1991-01-01

    The regulatory regions for 119 Escherichia coli promoters have been analyzed, and the locations of the regulatory sites have been cataloged. The following observations emerge. (i) More than 95% of promoters are coregulated with at least one other promoter. (ii) Virtually all sigma 70 promoters contain at least one regulatory site in a proximal position, touching at least position -65 with respect to the start point of transcription. There are not yet clear examples of upstream regulation in the absence of a proximal site. (iii) Operators within regulons appear in very variable proximal positions. By contrast, the proximal activation sites of regulons are much more fixed. (iv) There is a forbidden zone for activation elements downstream from approximately position -20 with respect to the start of transcription. By contrast, operators can occur throughout the proximal region. When activation elements appear in the forbidden zone, they repress. These latter examples usually involve autoregulation. (v) Approximately 40% of repressible promoters contain operator duplications. These occur either in certain regulons where duplication appears to be a requirement for repressor action or in promoters subject to complex regulation. (vi) Remote operator duplications occur in approximately 10% of repressible promoters. They generally appear when a multiple promoter region is coregulated by cyclic AMP receptor protein. (vii) Sigma 54 promoters do not require proximal or precisely positioned activator elements and are not generally subject to negative regulation. Rationales are presented for all of the above observations. PMID:1943993

  17. Chromosome Replication in Escherichia coli: Life on the Scales.

    PubMed

    Norris, Vic; Amar, Patrick

    2012-01-01

    At all levels of Life, systems evolve on the 'scales of equilibria'. At the level of bacteria, the individual cell must favor one of two opposing strategies and either take risks to grow or avoid risks to survive. It has been proposed in the Dualism hypothesis that the growth and survival strategies depend on non-equilibrium and equilibrium hyperstructures, respectively. It has been further proposed that the cell cycle itself is the way cells manage to balance the ratios of these types of hyperstructure so as to achieve the compromise solution of living on the two scales. Here, we attempt to re-interpret a major event, the initiation of chromosome replication in Escherichia coli, in the light of scales of equilibria. This entails thinking in terms of hyperstructures as responsible for intensity sensing and quantity sensing and how this sensing might help explain the role of the DnaA protein in initiation of replication. We outline experiments and an automaton approach to the cell cycle that should test and refine the scales concept. PMID:25371267

  18. Transcriptional Regulation of the esp Genes of Enterohemorrhagic Escherichia coli

    PubMed Central

    Beltrametti, Fabrizio; Kresse, Andreas U.; Guzmán, Carlos A.

    1999-01-01

    We have determined that the genes encoding the secreted proteins EspA, EspD, and EspB of enterohemorrhagic Escherichia coli (EHEC) are organized in a single operon. The esp operon is controlled by a promoter located 94 bp upstream from the ATG start codon of the espA gene. The promoter is activated in the early logarithmic growth phase, upon bacterial contact with eukaryotic cells and in response to Ca2+, Mn2+, and HEPES. Transcription of the esp operon seems to be switched off in tightly attached bacteria. The activation process is regulated by osmolarity (induction at high osmolarities), modulated by temperature, and influenced by the degree of DNA supercoiling. Transcription is ?S dependent, and the H-NS protein contributes to its fine tuning. Identification of the factors involved in activation of the esp operon and the signals responsible for modulation may facilitate understanding of the underlying molecular events leading to sequential expression of virulence factors during natural infections caused by EHEC. PMID:10348852

  19. Interaction of enteroaggregative Escherichia coli with salad leaves.

    PubMed

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

    2009-08-01

    Enteroaggregative Escherichia coli (EAEC) are important human pathogens. However, their environmental reservoir is unknown. As fresh salad leaves are increasingly recognized as an important environmental vector for human pathogens, we investigated leaf attachment capability of EAEC strains. We found that binding of clinical EAEC isolates to leaves from Eruca vesicaria (commonly known as rocket or arugula) can be divided into high, moderate and low adherent phenotypes. Using the prototype EAEC strain 042 to investigate the underlining mechanisms involved in leaf attachment, we found small attached bacterial aggregates over the entire leaf surface and dense bacterial attachment to the guard cell of the stomata. An aaf 042 mutant lost the ability to bind the epidermis while retaining stomatal adherence. In contrast, a fliC 042 mutant retained the ability to bind the epidermis but lost stomatal tropism. These results show that multiple adherence factors are involved in the interaction of EAEC with leaves, that EAEC uses similar colonization factors to bind mucosal and leaf surfaces and that fresh produce might be an important reservoir of EAEC strains. PMID:23765852

  20. Swimming patterns and dynamics of simulated Escherichia coli bacteria

    PubMed Central

    Zonia, Laura; Bray, Dennis

    2009-01-01

    A spatially and temporally realistic simulation of Escherichia coli chemotaxis was used to investigate the swimming patterns of wild-type and mutant bacteria within a rectangular arena in response to chemoattractant gradients. Swimming dynamics were analysed during long time series with phase-space trajectories, power spectra and estimations of fractal dimensions (FDs). Cell movement displayed complex trajectories in the phase space owing to interaction of multiple attractors that captured runs and tumbles. Deletion of enzymes responsible for adaptation (CheR and CheB) restricted the pattern of bacterial swimming in the absence of a gradient. In the presence of a gradient, there was a strong increase in trajectories arising from runs and attenuation of those arising from tumbles. Similar dynamics were observed for mutants lacking CheY, which are unable to tumble. The deletion of CheR, CheB and CheY also caused significant shifts in chemotaxis spectral frequencies. Rescaled range analysis and estimation of FD suggest that wild-type bacteria display characteristics of fractional Brownian motion with positive correlation between past and future events. These results reveal an underlying order in bacterial swimming dynamics, which enables a chemotactic search strategy conforming to a fractal walk. PMID:19324687

  1. Metabolism of L-glyceraldehyde 3-phosphate in Escherichia coli

    SciTech Connect

    Kalyananda, M.K.G.S.; Engel, R.; Tropp, B.E.

    1987-06-01

    When either /sup 3/H-labeled L-glyceraldehyde or /sup 3/H-labeled L-glyceraldehyde 3-phosphate (GAP) was added to cultures of Escherichia coli, the phosphoglycerides were labeled. More than 81% of the label appeared in the backbone of the phosphoglycerides. Chromatographic analyses of the labeled phosphoglycerides revealed that the label was normally distributed into phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin. These results suggest that L-glyceraldehyde is phosphorylated and the resultant L-GAP is converted into sn-glycerol 3-phosphate (G3P) before being incorporated into the bacterial phosphoglycerides. Cell-free bacterial extracts catalyzed an NADPH-dependent reduction of L-GAP to sn-G3P. The partially purified enzyme was specific for L-GAP and recognized neither D-GAP nor dihydroxyacetone phosphate as a substrate. NADH could not replace NADPH as a coenzyme. The L-GAP:NADPH oxidoreductase had an apparent K/sub m/ of 28 and 35 ..mu..M for L-GAP and NADPH, respectively. The enzyme was insensitive to sulfhydryl reagents and had a pH optimum of approximately 6.6. The phosphonic acid analog of GAP, 3-hydroxy-4-oxobutyl-1-phosphonate, was a substrate for the reductase, with an apparent K/sub m/ of 280 ..mu..M.

  2. Engineering modular ester fermentative pathways in Escherichia coli.

    PubMed

    Layton, Donovan S; Trinh, Cong T

    2014-10-01

    Sensation profiles are observed all around us and are made up of many different molecules, such as esters. These profiles can be mimicked in everyday items for their uses in foods, beverages, cosmetics, perfumes, solvents, and biofuels. Here, we developed a systematic 'natural' way to derive these products via fermentative biosynthesis. Each ester fermentative pathway was designed as an exchangeable ester production module for generating two precursors- alcohols and acyl-CoAs that were condensed by an alcohol acyltransferase to produce a combinatorial library of unique esters. As a proof-of-principle, we coupled these ester modules with an engineered, modular, Escherichia coli chassis in a plug-and-play fashion to create microbial cell factories for enhanced anaerobic production of a butyrate ester library. We demonstrated tight coupling between the modular chassis and ester modules for enhanced product biosynthesis, an engineered phenotype useful for directed metabolic pathway evolution. Compared to the wildtype, the engineered cell factories yielded up to 48 fold increase in butyrate ester production from glucose. PMID:25281839

  3. Conformational Dynamics of DNA Repair by Escherichia coli Endonuclease III.

    PubMed

    Kuznetsov, Nikita A; Kladova, Olga A; Kuznetsova, Alexandra A; Ishchenko, Alexander A; Saparbaev, Murat K; Zharkov, Dmitry O; Fedorova, Olga S

    2015-06-01

    Escherichia coli endonuclease III (Endo III or Nth) is a DNA glycosylase with a broad substrate specificity for oxidized or reduced pyrimidine bases. Endo III possesses two types of activities: N-glycosylase (hydrolysis of the N-glycosidic bond) and AP lyase (elimination of the 3'-phosphate of the AP-site). We report a pre-steady-state kinetic analysis of structural rearrangements of the DNA substrates and uncleavable ligands during their interaction with Endo III. Oligonucleotide duplexes containing 5,6-dihydrouracil, a natural abasic site, its tetrahydrofuran analog, and undamaged duplexes carried fluorescent DNA base analogs 2-aminopurine and 1,3-diaza-2-oxophenoxazine as environment-sensitive reporter groups. The results suggest that Endo III induces several fast sequential conformational changes in DNA during binding, lesion recognition, and adjustment to a catalytically competent conformation. A comparison of two fluorophores allowed us to distinguish between the events occurring in the damaged and undamaged DNA strand. Combining our data with the available structures of Endo III, we conclude that this glycosylase uses a multistep mechanism of damage recognition, which likely involves Gln(41) and Leu(81) as DNA lesion sensors. PMID:25869130

  4. Hydroxylated naphthoquinones as substrates for Escherichia coli anaerobic reductases.

    PubMed Central

    Rothery, R A; Chatterjee, I; Kiema, G; McDermott, M T; Weiner, J H

    1998-01-01

    We have used two hydroxylated naphthoquinol menaquinol analogues, reduced plumbagin (PBH2, 5-hydroxy-2-methyl-1,4-naphthoquinol) and reduced lapachol [LPCH2, 2-hydroxy-3-(3-methyl-2-butenyl)-1, 4-naphthoquinol], as substrates for Escherichia coli anaerobic reductases. These compounds have optical, solubility and redox properties that make them suitable for use in studies of the enzymology of menaquinol oxidation. Oxidized plumbagin and oxidized lapachol have well resolved absorbances at 419 nm (epsilon=3.95 mM-1. cm-1) and 481 nm (epsilon=2.66 mM-1.cm-1) respectively (in Mops/KOH buffer, pH 7.0). PBH2 is a good substrate for nitrate reductase A (Km=282+/-28 microM, kcat=120+/-6 s-1) and fumarate reductase (Km=155+/-24 microM, kcat=30+/-2 s-1), but not for DMSO reductase. LPCH2 is a good substrate for nitrate reductase A (Km=57+/-35 microM, kcat=68+/-13 s-1), fumarate reductase (Km=85+/-27 microM, kcat=74+/-6 s-1) and DMSO reductase (Km=238+/-30 microM, kcat=191+/-21 s-1). The sensitivity of enzymic LPCH2 and PBH2 oxidation to 2-n-heptyl-4-hydroxyquinoline N-oxide inhibition is consistent with their oxidation occurring at sites of physiological quinol binding. PMID:9576848

  5. Response surface methodology of nitrilase production by recombinant Escherichia coli

    PubMed Central

    Dubey, Sachin; Singh, Amit; Banerjee, Uttam C.

    2011-01-01

    Growth and nitrilase production by recombinant Escherichia coli cells harbouring pET 21 (b) plasmid, for the expression of Pseudomonas putida nitrilase were improved using response surface methodology. Central composite design was used for obtaining ideal concentration of critical medium components which include fructose, tryptone, yeast extract and lactose. The optimal values for the concentration of fructose, tryptone, yeast extract and lactose were found to be 1.13, 2.26, 3.25 and 0.9 % (w/v), respectively. Here, fructose served as carbon source for the growth while lactose was preferably used as inducer for the expression of foreign protein. Yeast extract in the medium was used as a growth promoter while tryptone was added as a major nitrogen source. Using this optimized medium, an experimental growth of 6.67 (OD at 600 nm) and nitrilase activity of 27.13 U/ml was achieved. This approach for medium development led to an enhancement of the growth and enzyme activity by 1.4 and 2.2 times, respectively, as compared to the un-optimized medium. PMID:24031726

  6. Characterization of the Escherichia coli Antifungal Protein PPEBL21

    PubMed Central

    Yadav, V.; Mandhan, R.; Kumar, M.; Gupta, J.; Sharma, G. L.

    2010-01-01

    An antifungal protein isolated from Escherichia coli BL21 (PPEBL21) and predicted to be alcohol dehydrogenase (ADH) was subjected to biological characterization. The PPEBL21, indeed, demonstrated propionaldehyde-specific ADH activity. The Km and Vmax of PPEBL21 were found to be 644.8 ?M and 1.2?U/mg, respectively. In-gel activity assay also showed that PPEBL21 was a propionaldehyde-specific ADH. The pI of PPEBL21 was observed to be 7.8. PPEBL21 was found to be stable up to a temperature of 40°C with optimum activity at pH 7.5. The decrease in pH decreased the activity of PPEBL21. These results suggested that PPEBL21 having alcohol dehydrogenase activity and stability at significantly high temperature might be an important lead antifungal molecule. Experiments were performed to identify the possible target of PPEBL21 in the pathogen A. fumigatus. Results revealed that PPEBL21 inhibited completely the expression of a 16?kDa protein in A. fumigatus. The?16 kDa protein of A. fumigatus targeted by PPEBL21 was identified as a hypothetical protein by peptide mass fingerprinting. It is thus hypothesized that a 16?kDa factor is essentially required by A. fumigatus for survival and its impaired synthesis due to treatment with PPEBL21 may lead to the death of pathogen. PMID:20490270

  7. Noise characteristics of the Escherichia coli rotary motor

    PubMed Central

    2011-01-01

    Background The chemotaxis pathway in the bacterium Escherichia coli allows cells to detect changes in external ligand concentration (e.g. nutrients). The pathway regulates the flagellated rotary motors and hence the cells' swimming behaviour, steering them towards more favourable environments. While the molecular components are well characterised, the motor behaviour measured by tethered cell experiments has been difficult to interpret. Results We study the effects of sensing and signalling noise on the motor behaviour. Specifically, we consider fluctuations stemming from ligand concentration, receptor switching between their signalling states, adaptation, modification of proteins by phosphorylation, and motor switching between its two rotational states. We develop a model which includes all signalling steps in the pathway, and discuss a simplified version, which captures the essential features of the full model. We find that the noise characteristics of the motor contain signatures from all these processes, albeit with varying magnitudes. Conclusions Our analysis allows us to address how cell-to-cell variation affects motor behaviour and the question of optimal pathway design. A similar comprehensive analysis can be applied to other two-component signalling pathways. PMID:21951560

  8. High Recombinant Frequency in Extraintestinal Pathogenic Escherichia coli Strains.

    PubMed

    Rodríguez-Beltrán, Jerónimo; Tourret, Jérôme; Tenaillon, Olivier; López, Elena; Bourdelier, Emmanuelle; Costas, Coloma; Matic, Ivan; Denamur, Erick; Blázquez, Jesús

    2015-07-01

    Homologous recombination promotes genetic diversity by facilitating the integration of foreign DNA and intrachromosomal gene shuffling. It has been hypothesized that if recombination is variable among strains, selection should favor higher recombination rates among pathogens, as they face additional selection pressures from host defenses. To test this hypothesis we have developed a plasmid-based method for estimating the rate of recombination independently of other factors such as DNA transfer, selective processes, and mutational interference. Our results with 160 human commensal and extraintestinal pathogenic Escherichia coli (ExPEC) isolates show that the recombinant frequencies are extremely diverse (ranging 9 orders of magnitude) and plastic (they are profoundly affected by growth in urine, a condition commonly encountered by ExPEC). We find that the frequency of recombination is biased by strain lifestyle, as ExPEC isolates display strikingly higher recombination rates than their commensal counterparts. Furthermore, the presence of virulence factors is positively associated with higher recombination frequencies. These results suggest selection for high homologous recombination capacity, which may result in a higher evolvability for pathogens compared with commensals. PMID:25804522

  9. Activity and interaction of trimethoprim and sulphamethoxazole against Escherichia coli.

    PubMed Central

    Greenwood, D; O'Grady, F

    1976-01-01

    The activity of trimethoprim (TMP) and sulphamethoxazole (SMX), alone and in combination, against a sensitive strain of Escherichia coli was investigated in turbidimetric systems. In a static system in which the conditions of exposure of bacteria to drug resembled those of conventional minimum inhibitory concentration (MIC) titrations, both TMP and SMX exhibited antibacterial activity at concentrations well below the conventionally determined MIC, but regrowth occured at these concentrations during the overnight incubation period due to the emergence of adaptively resistant bacteria. Tests of combined drug action in the static turbidimetric system revealed even more synergic interaction than was apparent in conventional MIC tests. It is suggested that an important component of overall synergic interaction is the mutual suppression of adaptive "resistance" to the other agent. Studies in an in vitro model which simulates the hydrokinetic features of the urinary bladder showed that concentrations of TMP and SMX below the conventionally determined MIC inhibited the growth even of extremely dense bacterial populations so long as the concentration of drug was maintained. The response of cultures exposed to combinations of TMP and SMX in this system was so dominated by the effect of TMP that no synergic interaction with SMX was noted at concentrations of the drugs which are achievable in urine. PMID:777036

  10. Activity and interaction of trimethoprim and sulphamethoxazole against Escherichia coli.

    PubMed

    Greenwood, D; O'Grady, F

    1976-02-01

    The activity of trimethoprim (TMP) and sulphamethoxazole (SMX), alone and in combination, against a sensitive strain of Escherichia coli was investigated in turbidimetric systems. In a static system in which the conditions of exposure of bacteria to drug resembled those of conventional minimum inhibitory concentration (MIC) titrations, both TMP and SMX exhibited antibacterial activity at concentrations well below the conventionally determined MIC, but regrowth occured at these concentrations during the overnight incubation period due to the emergence of adaptively resistant bacteria. Tests of combined drug action in the static turbidimetric system revealed even more synergic interaction than was apparent in conventional MIC tests. It is suggested that an important component of overall synergic interaction is the mutual suppression of adaptive "resistance" to the other agent. Studies in an in vitro model which simulates the hydrokinetic features of the urinary bladder showed that concentrations of TMP and SMX below the conventionally determined MIC inhibited the growth even of extremely dense bacterial populations so long as the concentration of drug was maintained. The response of cultures exposed to combinations of TMP and SMX in this system was so dominated by the effect of TMP that no synergic interaction with SMX was noted at concentrations of the drugs which are achievable in urine. PMID:777036

  11. Massive Diversification in Aging Colonies of Escherichia coli

    PubMed Central

    Saint-Ruf, Claude; Garfa-Traoré, Meriem; Collin, Valérie; Cordier, Corinne; Franceschi, Christine

    2014-01-01

    The evolutionary success of bacteria depends greatly on their capacity to continually generate phenotypic diversity. Structured environments are particularly favorable for diversification because of attenuated clonal interference, which renders selective sweeps nearly impossible and enhances opportunities for adaptive radiation. We examined at the microscale level the emergence and the spatial and temporal dynamics of phenotypic diversity and their underlying causes in Escherichia coli colonies. An important dynamic heterogeneity in the growth, metabolic activity, morphology, gene expression patterns, stress response induction, and death patterns among cells within colonies was observed. Genetic analysis indicated that the phenotypic variation resulted mostly from mutations and that indole production, oxidative stress, and the RpoS-regulated general stress response played an important role in the generation of diversity. We observed the emergence and persistence of phenotypic variants within single colonies that exhibited variable fitness compared to the parental strain. Some variants showed improved capacity to produce biofilms, whereas others were able to use different nutrients or to tolerate antibiotics or oxidative stress. Taken together, our data show that bacterial colonies provide an ecological opportunity for the generation and maintenance of vast phenotypic diversity, which may increase the probability of population survival in unpredictable environments. PMID:24982303

  12. Filamentous Escherichia coli cells swimming in tapered microcapillaries.

    PubMed

    Jaimes-Lizcano, Yuly A; Hunn, Dayton D; Papadopoulos, Kyriakos D

    2014-04-01

    This study analyzed the swimming characteristics of filamentous Escherichia coli cells inside tapered capillaries with a diameter decreasing from 700 ?m to 4 ?m and a mean body length of 27.8 ?m ± 11.9 ?m. Cells that were pre-oriented towards the narrower diameter section of the tapered capillary swam with high directional persistence, following conical-helix trajectories along the capillary wall. The confinement of the tapered capillary significantly diminished the mean swimming speed of filamentous cells when compared to their unrestricted mean swimming speed. The cell body rotation of individual filamentous bacteria decreased along the tapered direction, likely due to increased steric interactions with the capillary wall. Filamentous cells that swam under imposed flow rates ranging from 0.2 ?l/min to 0.8 ?l/min showed positive rheotaxis inside the 150 ?m-350 ?m diameter region of the tapered capillary. Depending on the imposed flow rate, none of the bacteria could advance beyond a critical diameter in the tapered capillary. This critical diameter is likely to be the position of the maximum shear rate they can tolerate without being flushed away. This work showed experimental evidence of how a simple flow constriction such as a tapered tube forms a hydrodynamic barrier that can deter the advance of bacterial rheotaxis. PMID:24566556

  13. Endonuclease IV of Escherichia coli is induced by paraquat

    SciTech Connect

    Chan, E.; Weiss, B.

    1987-05-01

    The addition of paraquat (methyl viologen) to a growing culture of Escherichia coli K-12 led within 1 hr to a 10- to 20-fold increase in the level of endonuclease IV, a DNase for apurinic/apyrimidinic sites. The induction was blocked by chloramphenicol. Increases of 3-fold or more were also seen with plumbagin, menadione, and phenazine methosulfate. H/sub 2/O/sub 2/ produced no more than a 2-fold increase in endonuclease IV activity. The following agents had no significant effect: streptonigrin, nitrofurantoin, tert-butyl hydroperoxide, ..gamma.. rays, 260-nm UV radiation, methyl methanesulfonate, mitomycin C, and ascorbate. Paraquat, plumbagin, menadione, and phenazine methosulfate are known to generate superoxide radical anions via redox cycling in vivo. A mutant lacking superoxide dismutase was unusually sensitive to induction by paraquat. In addition, endonuclease IV could be induced by merely growing the mutant in pure O/sub 2/. The levels of endonuclease IV in uninduced or paraquat-treated cells were unaffected by mutations of oxyR, a H/sub 2/O/sub 2/-inducible gene that governs an oxidative-stress regulon. The results indicate that endonuclease IV is an inducible DNA-repair enzyme and that its induction can be mediated via the production of superoxide radicals.

  14. PotD protein stimulates biofilm formation by Escherichia coli.

    PubMed

    Zhang, Xiao; Zhang, Yuzhen; Liu, Junjun; Liu, Honglei

    2013-07-01

    In natural environments bacteria often adopt a biofilm-growth mode. PotD is a spermidine/putrescine-binding periplasmic protein belonging to polyamine transport system and we have examined its role during biofilm formation and for planktonic growth in Escherichia coli BL21(DE3) strains that either over-express PotD (PotD+), or under-express it (PotDi) and also in a control strain with vector pET26b(+) (PotD0). The three strains displayed similar growth in planktonic growth-mode, but over expression of PotD protein greatly stimulated the formation of biofilms, while less biofilm formed by strain PotDi in comparison to strain PotD0. The expressions of five genes, recA, sfiA, groEL, groES, and gyrA, were increasingly expressed in PotD+ biofilm cells. Thus, PotD is likely to change the rate of polyamine synthesis, which stimulates the expression of SOS genes and biofilm formation. PMID:23539287

  15. Transposon Mutagenesis Identifies Uropathogenic Escherichia coli Biofilm Factors

    PubMed Central

    Hadjifrangiskou, Maria; Gu, Alice P.; Pinkner, Jerome S.; Kostakioti, Maria; Zhang, Ellisa W.; Greene, Sarah E.

    2012-01-01

    Uropathogenic Escherichia coli (UPEC), which accounts for 85% of urinary tract infections (UTI), assembles biofilms in diverse environments, including the host. Besides forming biofilms on biotic surfaces and catheters, UPEC has evolved an intracellular pathogenic cascade that culminates in the formation of biofilm-like intracellular bacterial communities (IBCs) within bladder epithelial cells. Rapid bacterial replication during IBC formation augments a build-up in bacterial numbers and persistence within the host. Relatively little is known about factors mediating UPEC biofilm formation and how these overlap with IBC formation. To address this gap, we screened a UPEC transposon mutant library in three in vitro biofilm conditions: Luria broth (LB)-polyvinyl chloride (PVC), YESCA (yeast extract-Casamino Acids)-PVC, and YESCA-pellicle that are dependent on type 1 pili (LB) and curli (YESCA), respectively. Flagella are important in all three conditions. Mutants were identified that had biofilm defects in all three conditions but had no significant effects on the expression of type 1 pili, curli, or flagella. Thus, this approach uncovered a comprehensive inventory of novel effectors and regulators that are involved in UPEC biofilm formation under multiple conditions. A subset of these mutants was found to be dramatically attenuated and unable to form IBCs in a murine model of UTI. Collectively, this study expands our insights into UPEC multicellular behavior that may provide insights into IBC formation and virulence. PMID:22984258

  16. Production of salidroside in metabolically engineered Escherichia coli

    PubMed Central

    Bai, Yanfen; Bi, Huiping; Zhuang, Yibin; Liu, Chang; Cai, Tao; Liu, Xiaonan; Zhang, Xueli; Liu, Tao; Ma, Yanhe

    2014-01-01

    Salidroside (1) is the most important bioactive component of Rhodiola (also called as “Tibetan Ginseng”), which is a valuable medicinal herb exhibiting several adaptogenic properties. Due to the inefficiency of plant extraction and chemical synthesis, the supply of salidroside (1) is currently limited. Herein, we achieved unprecedented biosynthesis of salidroside (1) from glucose in a microorganism. First, the pyruvate decarboxylase ARO10 and endogenous alcohol dehydrogenases were recruited to convert 4-hydroxyphenylpyruvate (2), an intermediate of L-tyrosine pathway, to tyrosol (3) in Escherichia coli. Subsequently, tyrosol production was improved by overexpressing the pathway genes, and by eliminating competing pathways and feedback inhibition. Finally, by introducing Rhodiola-derived glycosyltransferase UGT73B6 into the above-mentioned recombinant strain, salidroside (1) was produced with a titer of 56.9?mg/L. Interestingly, the Rhodiola-derived glycosyltransferase, UGT73B6, also catalyzed the attachment of glucose to the phenol position of tyrosol (3) to form icariside D2 (4), which was not reported in any previous literatures. PMID:25323006

  17. Multiscale Spatial Organization of RNA Polymerase in Escherichia coli

    PubMed Central

    Endesfelder, Ulrike; Finan, Kieran; Holden, Seamus J.; Cook, Peter R.; Kapanidis, Achillefs N.; Heilemann, Mike

    2013-01-01

    Nucleic acid synthesis is spatially organized in many organisms. In bacteria, however, the spatial distribution of transcription remains obscure, owing largely to the diffraction limit of conventional light microscopy (200–300 nm). Here, we use photoactivated localization microscopy to localize individual molecules of RNA polymerase (RNAP) in Escherichia coli with a spatial resolution of ?40 nm. In cells growing rapidly in nutrient-rich media, we find that RNAP is organized in 2–8 bands. The band number scaled directly with cell size (and so with the chromosome number), and bands often contained clusters of >70 tightly packed RNAPs (possibly engaged on one long ribosomal RNA operon of 6000 bp) and clusters of such clusters (perhaps reflecting a structure like the eukaryotic nucleolus where many different ribosomal RNA operons are transcribed). In nutrient-poor media, RNAPs were located in only 1–2 bands; within these bands, a disproportionate number of RNAPs were found in clusters containing ?20–50 RNAPs. Apart from their importance for bacterial transcription, our studies pave the way for molecular-level analysis of several cellular processes at the nanometer scale. PMID:23823236

  18. Thermolabile antifreeze protein produced in Escherichia coli for structural analysis.

    PubMed

    Lin, Feng-Hsu; Sun, Tianjun; Fletcher, Garth L; Davies, Peter L

    2012-03-01

    The only hyperactive antifreeze protein (AFP) found to date in fishes is an extreme variant of the 3-kDa, alpha-helical, alanine-rich type I AFP, which is referred to here as type Ih. Purification of the 33-kDa homodimeric AFP Ih from a natural source was hampered by its low levels in fish plasma; by the need to remove the more abundant smaller isoforms; and by its extreme thermolability. Moreover, ice affinity as a purification tool was spoiled by the tendency of fish IgM antibodies to bind to ice in the presence of AFPs. In order to produce enough protein for crystallography we expressed AFP Ih as a recombinant protein in the Arctic Express® strain of Escherichia coli at 12 °C, just below the thermal denaturation temperature of 16-18 °C. His-tags were not useful because they compromised the activity and yield of AFP Ih. But in the absence of fish antibodies we were able to recover 10-mg quantities of the antifreeze protein using two cycles of ice affinity purification followed by anion-exchange chromatography to remove contaminating chaperones. The purified recombinant AFP Ih yielded diffraction-quality crystals with an extremely asymmetrical unit cell. By transferring the genes of the chaperones into a methionine auxotroph we were able to grow this host at low temperatures and produce sufficient selenomethionine-labeled AFP Ih for crystallography. PMID:22155222

  19. Overexpression of metabolic enzymes at the junction of glycolylsis and the TCA cycle in Escherichia coli: physiological effects and application 

    E-print Network

    Spitzer, Richard G.

    1999-01-01

    The metabolism of Escherichia coli has central importance in biochemical engineering, metabolic engineering, and molecular biology. This study relates to all three disciplines. In biochemical engineering, previous studies ...

  20. ORIGINAL RESEARCH Shigella Strains Are Not Clones of Escherichia coli

    E-print Network

    Hao, Bailin

    phenotyping experiments and several recent molecular studies put Shigella within the species E. coli. However, are distinct from E. coli strains, and form sister species to E. coli within the genus Esch- erichia. In view. We hope that the present report may promote further in-depth study of the Shigella-E. coli