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Sample records for escherichia coli effect

  1. Synergistic effects in mixed Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Reisner, A.; Holler, B.M.; Molin, Søren

    2006-01-01

    Bacterial biofilms, often composed of multiple species and genetically distinct strains, develop under complex influences of cell-cell interactions. Although detailed knowledge about the mechanisms underlying formation of single-species laboratory biofilms has emerged, little is known about...... the pathways governing development of more complex heterogeneous communities. In this study, we established a laboratory model where biofilm-stimulating effects due to interactions between genetically diverse strains of Escherichia coli were monitored. Synergistic induction of biofilm formation resulting from...... the cocultivation of 403 undomesticated E. coli strains with a characterized E. coli K-12 strain was detected at a significant frequency. The survey suggests that different mechanisms underlie the observed stimulation, yet synergistic development of biofilm within the subset of E. coli isolates (n = 56) exhibiting...

  2. Escherichia Coli

    Science.gov (United States)

    Goodsell, David S.

    2009-01-01

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

  3. Effect of high pressurized carbon dioxide on Escherichia coli ...

    African Journals Online (AJOL)

    Carbon dioxide at high pressure can retard microbial growth and sometimes kill microorganisms depending on values of applied pressure, temperature and exposure time. In this study the effect of high pressurised carbon dioxide (HPCD) on Escherichia coli was investigated. Culture of E. coli was subjected to high ...

  4. Effects of recombinant human collagen VI from Escherichia coli on ...

    African Journals Online (AJOL)

    Jane

    2011-07-20

    Jul 20, 2011 ... In this study, we reported the cloning and over expression of a gene coding for human collagen peptide. (CP6) in Escherichia coli and investigated the protective effects of CP6 on UVA-irradiated human skin fibroblasts cells. The collagen peptide (CP6) was highly soluble and the expression level was.

  5. Peptide nucleic acid (PNA) antisense effects in Escherichia coli

    DEFF Research Database (Denmark)

    Good, L; Nielsen, P E

    1999-01-01

    Antisense peptide nucleic acid (PNA) can be used to control cell growth, gene expression and growth phenotypes in the bacteria Escherichia coli. PNAs targeted to the RNA components of the ribosome can inhibit translation and cell growth, and PNAs targeted to mRNA can limit gene expression with gene...... and sequence specificity. In an E. coli cell extract, efficient inhibition is observed when using PNA concentrations in the nanomolar range, whereas micromolar concentrations are required for inhibition in growing cells. A mutant strain of E. coli that is more permeable to antibiotics also is more susceptible...... to antisense PNAs than the wild type. This chapter details methods for testing the antisense activities of PNA in E. coli. As an example of the specific antisense inhibition possible, we show the effects of an anti-beta-galactosidase PNA in comparison to control PNAs. With improvements in cell uptake...

  6. Mechanisms of the radioprotective effect of cysteamine in Escherichia coli

    International Nuclear Information System (INIS)

    Korystov, Yu.N.; Vexler, F.B.

    1988-01-01

    The values of the oxygen effect (m) and the maximal protective effect of cysteamine (DMF*) were estimated for four Escherichia coli strains: AB1157 (wild type), AB1886 (uvrA), AB2463 (recA), and p3478 (polA). A correlation made between DMF* and m as well as the kinetics of the increase of DMF with oxygen depletion showed that the protective effect of cysteamine is realized by three mechanisms: (i) anoxia achieved by oxygen reduction, with the DMF varying from 2.2 to 4.2 for different E. coli strains (this protection is the major contribution to the entire mechanism); (ii) lowering of the indirect radiation effect; i.e., for 50 mM cysteamine DMF does not exceed 1.1; and (iii) increase of the efficiency of enzymatic repair. The latter effect of cysteamine is registered only with the wild-type E. coli, the DMF being not less than 1.4

  7. Protective effects of indigenous Escherichia coli against a pathogenic E. coli challenge strain in pigs.

    Science.gov (United States)

    Vahjen, W; Cuisiniere, T; Zentek, J

    2017-10-13

    To investigate the inhibitory effect of indigenous enterobacteria on pathogenic Escherichia coli, a challenge trial with postweaning pigs was conducted. A pathogenic E. coli strain was administered to all animals and their health was closely monitored thereafter. Faecal samples were taken from three healthy and three diarrhoeic animals. Samples were cultivated on MacConkey agar and isolates were subcultured. A soft agar overlay assay was used to determine the inhibitory activity of the isolates. A total of 1,173 enterobacterial isolates were screened for their ability to inhibit the E. coli challenge strain. Colony forming units of enterobacteria on MacConkey agar were not different between healthy and diarrhoeic animals in the original samples. Furthermore, numbers of isolates per animal were also not significantly different between healthy (482 isolates) and diarrhoeic animals (691 isolates). A total of 43 isolates (3.7%) with inhibitory activity against the pathogenic E. coli challenge strain were detected. All inhibitory isolates were identified as E. coli via MALDI-TOF. The isolates belonged to the phylotypes A, C and E. Many isolates (67.4%) were commensal E. coli without relevant porcine pathogenic factors, but toxin- and fimbrial genes (stx2e, fae, estIb, elt1a, fas, fan) were detected in 14 inhibitory isolates. Healthy animals showed significantly (P=0.003) more inhibitory isolates (36 of 482 isolates; 7.5%) than diseased animals (7 of 691 isolates; 1.0%). There were no significant correlations regarding phylotype or pathogenic factors between healthy and diseased animals. This study has shown that a small proportion of indigenous E. coli is able to inhibit in vitro growth of a pathogenic E. coli strain in pigs. Furthermore, healthy animals possess significantly more inhibitory E. coli strains than diarrhoeic animals. The inhibition of pathogenic E. coli by specific indigenous E. coli strains may be an underlying principle for the containment of pathogenic

  8. Escherichia coli pathotypes

    Science.gov (United States)

    Escherichia coli strains are important commensals of the intestinal tract of humans and animals; however, pathogenic strains, including diarrhea-inducing E. coli and extraintestinal pathogenic E. coli. Intestinal E. coli pathotypes may cause a dehydrating watery diarrhea, or more severe diseases su...

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

    International Nuclear Information System (INIS)

    Andersson, R.; Schalen, C.; Tranberg, K.G.

    1991-01-01

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

  10. Effect of visible range electromagnetic radiations on Escherichia coli ...

    African Journals Online (AJOL)

    Background: Escherichia coli is the agent responsible for a range of clinical diseases. With emerging antimicrobial resistance, other treatment options including solar/photo-therapy are becoming increasingly common. Visible Range Radiation Therapy/Colour Therapy is an emerging technique in the field of ...

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

  13. Effect of phytoplankton on Escherichia coli survival in laboratory microcosms

    Science.gov (United States)

    Fecal contamination of water sources is an important water quality issue for agricultural irrigation ponds. Escherichia coli is a common microbial indicator used to evaluate recreational and irrigation water quality. Nuisance algae commonly grow in low- or no-flow irrigation water source The objecti...

  14. Antimutagenic effect of isocyanates and related compounds in escherichia coli

    International Nuclear Information System (INIS)

    Kawazoe, Yutaka; Kato, Masanari

    1982-01-01

    Isocyanates and isothiocyanates have been suggested to inactivate enzymes involved in the metabolic activation of chemical carcinogens and the repair of DNA damage. These compounds decrease the mutability of a tester strain of Escherichia coli B under UV irradiation. This paper deals with the antimutagenicity of acylating agents, including isocyanates and isothiocyanates, and some anti-oxidants which are suspected to be anticarcinogenic. The results can be summarized as follows. (1) The antimutagenic effect observed in the present study operates on UV-induced mutagenesis but not on X-ray-induced mutagenesis. (2) This effect operates only on the wild-type strain, H/r30R, but not on Hs30R deficient in the excision repair system. (3) This effect may function through giving the irradiated cells a greater chance to carry out excision repair by prolonging the lag-period before entry into the S-phase. (4) The carbamoylating ability of isocyanates and isothiocyanates may be responsible for the antimutagenicity, but other type of reactivities may also be involved. These antimutagens also participate in inactivating enzymes relevant to the metabolic activation of mutagens, resulting in a decrease in the frequency of chemically induced mutagenesis. (author)

  15. Conjugation in Escherichia coli

    Science.gov (United States)

    Boyer, Herbert

    1966-01-01

    Boyer, Herbert (Yale University, New Haven, Conn.). Conjugation in Escherichia coli. J. Bacteriol. 91:1767–1772. 1966.—The sex factor of Escherichia coli K-12 was introduced into an E. coli B/r strain by circumventing the host-controlled modification and restriction incompatibilities known to exist between these closely related strains. The sexual properties of the constructed F+ B strain and its Hfr derivatives were examined. These studies showed that the E. coli strain B/r F+ and Hfr derivatives are similar to the E. coli strain K-12 F+ and Hfr derivatives. However, the site of sex factor integration was found to be dependent on the host genome. PMID:5327905

  16. Effect of enrofloxacin treatment on plasma endotoxin during bovine Escherichia coli mastitis

    NARCIS (Netherlands)

    Dosogne, H.; Meyer, E.; Sturk, A.; van Loon, J.; Massart-Leën, A. M.; Burvenich, C.

    2002-01-01

    OBJECTIVE AND DESIGN: To investigate the effect of enrofloxacin on endotoxin resorption during bovine Escherichia coli mastitis. ANIMALS: 12 healthy early post partum Holstein cows. TREATMENT: Mastitis was induced by intramammary infusion of 10(4) cfu E. coli P4:032. Six cows were treated twice

  17. Enterohemorrhagic Escherichia coli (EHEC

    Directory of Open Access Journals (Sweden)

    Abdullah Kilic

    2011-08-01

    Full Text Available Escherichia coli is a bacterium that is commonly found in the gut of humans and warm-blooded animals. Most strains of E. coli are harmless for human. E. coli O157:H7 is the most common member of a group of pathogenic E. coli strains known variously as enterohaemorrhagic, verocytotoxin-producing, or Shiga-toxin-producing organisms. EHEC bacterium is the major cause of haemorrhagic colitis and haemolytic uraemic syndrome. The reservoir of this pathogen appears to be mainly cattle and other ruminants such as camels. It is transmitted to humans primarily through consumption of contaminated foods. [TAF Prev Med Bull 2011; 10(4.000: 387-388

  18. ESCHERICHIA COLI AND STAPHYLOCOCCUS AUREUS

    African Journals Online (AJOL)

    DR. AMINU

    ABSTRACT. The bio-effects of the ethanol extracts from the leaf and stem of Momordica charantia were studied with the view to ascertain the medical usefulness ascribed to the plant by the locals. The plant parts, stem and leaf, revealed remarkable activity against Escherichia coli and Staphlococcus aureus. The leaves ...

  19. The antibacterial effect of four mouthwashes against streptococcus mutans and escherichia coli.

    Science.gov (United States)

    Ghapanchi, Janan; Lavaee, Fatemeh; Moattari, Afagh; Shakib, Mahmood

    2015-04-01

    To evaluate the antimicrobial properties of several mouthwash concentrations on oral Streptococcus mutans and Escherichia coli. The study was conducted at Shiraz Medicine School in 2011. Serial dilutions of Chlorohexidin, Oral B and Persica and Irsha (2,4,8,16,64,128) were prepared in Muller-Hinton media. Minimum inhibitory concentration was visually determined and defined as the lowest concentration of each oral washing which inhibited > 95% growth reduction compared to the growth control well. Chlorhexidine, Oral B and Irsha mouthwash inhibited Streptococcus mutans even with diluted concentrations. Also, Chlorhexidine and Oral B prohibited Escherichia coli with different potencies. But Persica had no antimicrobial activity against either Escherichia coli or Streptococcus mutans. Chlorhexidine, Irsha, and Oral B mouthwashes can be used for antimicrobial effects, especially on Streptococcus mutans. This chemical activity of mouthwashes is an adjuvant for mechanical removing of plaque. However, the antimicrobial effect of Persicaremains controversial.

  20. Antibiofilm Effects of Lactobacilli against Ciprofloxacin-Resistant Uropathogenic Escherichia coli strains in Pasteurized Milk

    Directory of Open Access Journals (Sweden)

    Mahsa Yeganeh

    2017-11-01

    Full Text Available  Background and Objective: Uropathogenic Escherichia coli-induced urinary tract infections are the most common uropathogenic Escherichia coli etiological agent. In addition, most of biofilms created by these bacteria can be regarded as a serious problem in the food industry. Foodborne diseases have always been considered an emerging public health concern throughout the world. Many outbreaks have been found to be associated with biofilms. Thus, the aim of the present study is to investigate the anti-adhesive effects of lactic acid bacteria against strains of Ciprofloxacin-Resistant Uropathogenic Escherichia coli using microbial techniques in pasteurized milk.Material and Methods: In this study, strains of Lactobacillus plantarum, Lactobacillus casei and Lactobacillus acidophilus were provided from Pasteur Institute of Iran. Twenty strains of Uropathogenic Escherichia coli-Induced Urinary Tract Infections were isolated from patients with urinary tract infection in Shahid Labbafinejad hospital of Iran. Eight strains with ability of biofilm formation were selected for microbial tests. All of these eight strains were resistant to ciprofloxacin. Disk diffusion method was used to assess the susceptibility of all isolates to the ten common antibiotics. Eight samples of Uropathogenic Escherichia coli were inoculated in pasteurized milk. The microtitre plate 100 method was used to detect anti-adhesive activity of lactobacilli supernatant.Results and Conclusion: Results showed that the eight human isolates were resistant to antibiotics. Isolate of number 4 was the most susceptible strains to antibiofilm effects of lactobacilli in the pasteurized milk. The anti-adhesive effects of lactobacilli on Uropathogenic were confirmed in all microbial tests. In this study, Lactobacillus plantarum revealed the highest inhibitory activity against Uropathogenic Escherichia coli 4 strain with inhibition zones of 42 mm. This strain was reported as a proper probiotic

  1. Effect of radiation doses rate on SOS response induction in irradiated Escherichia coli Cells

    International Nuclear Information System (INIS)

    Cuetara Lugo, Elizabeth B.; Fuentes Lorenzo, Jorge L.; Almeida Varela, Eliseo; Prieto Miranda, Enrique F.; Sanchez Lamar, Angel; Llagostera Casal, Montserrat

    2005-01-01

    The present work is aimed to study the effect of radiation dose rate on the induction of SOS response in Escherichia coli cells. We measured the induction of sul A reporter gene in PQ-37 (SOS Chromotest) cells. Lead devises were built with different diameter and these were used for diminishing the dose rate of PX- -30M irradiator. Our results show that radiation doses rate significantly modifies the induction of SOS response. Induction factor increases proportionally to doses rate in Escherichia coli cells defective to nucleotide excision repair (uvrA), but not in wild type cells. We conclude that the dose rate affects the level of induction of SOS response

  2. Mutations in Escherichia coli that effect sensitivity to oxygen

    International Nuclear Information System (INIS)

    Jamison, C.S.; Adler, H.I.

    1987-01-01

    Fifteen oxygen-sensitive (Oxy/sup s/) mutants of Escherichia coli were isolated after exposure to UV light. The mutants did not form macroscopic colonies when plated aerobically. They did form macroscopic colonies anaerobically. Oxygen, introduced during log phase, inhibited the growth of liquid cultures. The degree of inhibition was used to separate the mutants into three classes. Class I mutants did not grow after exposure to oxygen. Class II mutants were able to grow, but at a reduced rate and to a reduced final titer, when compared with the wild-type parent. Class III mutants formed filaments in response to oxygen. Genetic experiments indicated that the mutations map to six different chromosomal regions. The results of enzymatic assays indicated that 7 of the 10 class I mutants have low levels of catalase, peroxidase, superoxide dismutase, and respiratory enzymes when compared with the wild-type parent. Mutations in five of the seven class I mutants which have the low enzyme activities mapped within the region 8 to 13.5 min. P1 transduction data indicated that mutations in three of these five mutants, Oxy/sup s/-6, Oxy/sup s/-14, and Oxy/sup s/-17, mapped to 8.4 min. The correlation of low enzyme levels and mapping data suggest that a single gene may regulate several enzymes in response to oxygen. The remaining three class I mutants had wild-type levels of catalase, peroxidase, and superoxide dismutase, but decreased respiratory activity. The class II and III mutants had enzyme activities similar to those of the wild-type parent

  3. Thioredoxin from Escherichia coli

    International Nuclear Information System (INIS)

    Holmgren, A.; Ohlsson, I.; Grankvist, M.L.

    1978-01-01

    A competition radioimmunoassay for Escherichia coli thioredoxin using 125 I-labeled thioredoxin-S 2 and a double antibody technique was developed. The method permits determination of picomole amounts of thioredoxin in crude cell extracts and was used to study the localization of thioredoxin cell fractions. E. coli B was calculated to have approximately 10,000 copies of thioredoxin per cell mainly located in the soluble fraction after separation of the membrane and soluble fractions by gentle lysis and centrifugation. E. coli B tsnC mutants which are defective in the replication of phage T7 DNA in vivo and in vitro were examined for their content of thioredoxin. E. coli B tsnC 7004 contained no detectable level of thioredoxin in cell-free extracts examined under a variety of conditions. The results strongly suggest that tsnC 7004 is a nonsense or deletion mutant. Two other E. coli tsnC mutants, 7007 and 7008, contained detectable levels of thioredoxin in crude extracts as measured by thioredoxin reductase and gave similar immunoprecipitation reactions as the parent strain B/1. By radioimmunoassay incompletely cross-reacting material was present in both strains. These results show that tsnC 7007 and 7008 belong to a type of thioredoxin mutants with missence mutations in the thioredoxin gene affecting the function of thioredoxin as subunit in phage T7 DNA polymerase

  4. PART I. ESCHERICHIA COLI

    Directory of Open Access Journals (Sweden)

    Sanaa Mahdi Oraibi

    2016-11-01

    Full Text Available The presence of Escherichia coli in the air of facilities involved in management and composting of post-slaughter poultry wastes in selected plants of West Western Pomerania region was studied. Measurements were made on four dates in a variety of weather conditions during the year. The study was conducted at 5 objects that differ in the type of waste and the degree of preparation for composting. These were: chemical treatment and preliminary processing plant, liquid wastes reservoir, platform for preparation of materials for composting, storage of biological sediments, and composting facility. Measurement of bacteria count was carried out in accordance with the applicable procedures on selective chromogenic TBX medium. The assays revealed the presence of E. coli at all test objects, but not always on all measurement dates. It has been shown that the presence of E. coli was from 20 to 3047 CFU∙m-3 of air, although the largest quantities were most frequently detected in the air of the building for post-slaughter waste pre-treatment in chemical treatment plant.

  5. Effect of low concentrations of ozone on Escherichia coli chromosome

    Energy Technology Data Exchange (ETDEWEB)

    Hamelin, C; Chung, Y S

    1975-01-01

    The investigations reported here are an extension of previous work reported from the same laboratory, the aim of which is to demonstrate the potential of ozone to have mutagenic effects in man. Data indicate that ozone has the ability to induce mutation in a wide range of genes responsible for the nutritional properties of E. coli. They also indicate that there are a great number of mutant strains either more resistant or more sensitive to UV radiation than the parental strain; and there are numerous mucoid strains forming excessive amounts of capsular polysaccharide after treatment. It appears that ozone could be expected to produce mutation in all types of genes. Considering that these findings in the microbial system studied are associated with positive findings in in vivo cytogenetics-acute tests, and that extrapolation of mutation rates directly from experimental organisms to man can be done with confidence, it seems that even the very low concentrations of ozone which occur in certain weather conditions must be avoided. 17 references, 1 table.

  6. The Effect of Air Plasma on Sterilization of Escherichia coli in Dielectric Barrier Discharge

    International Nuclear Information System (INIS)

    Hu Miao; Guo Yun

    2012-01-01

    In this work, a Dielectric Barrier Discharge (DBD) air plasma was used to sterilize Escherichia coli (E. coli) on the surface of medical Polyethylene Terephthalate (PET) film. The leakage of cellular DNA and protein by optical absorbance measurement at 260 nm and 280 nm, together with transmission electron microscopy (TEM) about cell morphology were performed after sterilization to analyse inactivation mechanisms. The results indicated that the DBD air plasma was very effective in E. coli sterilization. The plasma germicidal efficiency depended on the plasma treatment time, the air-gap distance, and the applied voltage. Within 5 min of plasma treatment, the germicidal efficiency against E. coli could reach 99.99%. An etching action on cell membranes by electrons, ions and radicals is the primary mechanism for DBD air plasma sterilization, which leads to the effusion of cellular contents (DNA and protein) and bacterial death. (plasma technology)

  7. Anti-Escherichia coli effect of Hibiscus sabdariffa L. in a meat model

    Directory of Open Access Journals (Sweden)

    Marcelo Pinto PAIM

    Full Text Available Abstract Hibiscus sabdariffa L. is used in traditional medicine because of its bioactive properties, such as antioxidant and antibacterial. Escherichia coli is a Gram-negative bacteria and as an indicator of contamination in food. The aim of this work was to evaluate the anti-Escherichia coli effect and the change in pH on the control of aerobic mesophilic microorganisms, using hydroethanolic extract of H. sabdariffa L. in different concentrations in a meat model, verifying its potential as food additive for microbiological stability on ground beef during cooling storage. For the preparation of the treatments, the meat experimental units were elaborated with different concentrations of the vegetal extract (5, 10, 15 and 20%, ground beef and contaminated with E. coli. For pH evaluation, the meat experimental units were added different percentages of hydroethanolic extract. The H. sabdariffa L. antibacterial action reduced two logarithmic levels in practically all treatments. The best pH result was obtained in the meat containing 30% of the extract. The hydroethanolic extracts of Hibiscus sabdariffa L. showed anti-Escherichia coli activity in the presence of refrigerated ground beef. Analyzing the pH results and the count of aerobic mesophilic bacteria, it is possible this extract to be used as a natural food additive.

  8. Antibacterial effects of zinc oxide nanoparticles on Escherichia coli ...

    African Journals Online (AJOL)

    To study the antibacterial mechanisms, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to observe morphological changes of E. coli K88 treated with 0.8 μg/ml zinc oxide nanoparticles. The results reveal that zinc oxide nanoparticles could damage cell membranes, lead to leakage of ...

  9. ANIMAL ENTEROTOXIGENIC ESCHERICHIA COLI

    Science.gov (United States)

    Dubreuil, J. Daniel; Isaacson, Richard E.; Schifferli, Dieter M.

    2016-01-01

    Enterotoxigenic Escherichia coli (ETEC) is the most common cause of E. coli diarrhea in farm animals. ETEC are characterized by the ability to produce two types of virulence factors; adhesins that promote binding to specific enterocyte receptors for intestinal colonization and enterotoxins responsible for fluid secretion. The best-characterized adhesins are expressed in the context of fimbriae, such as the F4 (also designated K88), F5 (K99), F6 (987P), F17 and F18 fimbriae. Once established in the animal small intestine, ETEC produces enterotoxin(s) that lead to diarrhea. The enterotoxins belong to two major classes; heat-labile toxin that consist of one active and five binding subunits (LT), and heat-stable toxins that are small polypeptides (STa, STb, and EAST1). This chapter describes the disease and pathogenesis of animal ETEC, the corresponding virulence genes and protein products of these bacteria, their regulation and targets in animal hosts, as well as mechanisms of action. Furthermore, vaccines, inhibitors, probiotics and the identification of potential new targets identified by genomics are presented in the context of animal ETEC. PMID:27735786

  10. Effect of the oyster contaminated in Salmonella typhimurium and Escherichia coli; Efecto del ostion contaminado en Salmonella typhimurium y Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Brena V, M

    1992-08-15

    In this work the effect of the oyster contaminated in the species of bacteria better studied by its genetic composition these are the Salmonella typhimurium and the Escherichia coli and that its have been starting point for later radiobiological studies in superior organisms. Of this its have arisen two general lines. The research about the genotoxic effect of substances or mixtures in bacteria with the collaboration of the groups of Drosophila and X-ray Fluorescence analysis and on the other hand the study of the low doses of radiation also in bacteria. It is also treated the topic about the genetic effect of aromatic hydrocarbons in different biological systems. (Author)

  11. Sex-related effects of nutritional supplementation of Escherichia coli: relevance to eating disorders.

    Science.gov (United States)

    Tennoune, Naouel; Legrand, Romain; Ouelaa, Wassila; Breton, Jonathan; Lucas, Nicolas; Bole-Feysot, Christine; do Rego, Jean-Claude; Déchelotte, Pierre; Fetissov, Sergueï O

    2015-03-01

    The biological background of sex-related differences in the development of eating disorders (EDs) is unknown. Recent data showed that gut bacteria Escherichia coli induce autoantibodies against anorexigenic α-melanocyte-stimulating hormone (α-MSH) associated with psychopathology in ED. The aim of this study was to compare the effects of E. coli on feeding and autoantibodies against α-MSH and adrenocorticotropic hormone (ACTH), between female and male rats. Commensal E. coli K12 were given in a culture medium daily to adult Wistar rats by intragastric gavage over a 3-wk period; control rats received culture medium only. Before gavage, E. coli K12 DNA was detected in feces of female but not male rats. E. coli provision was accompanied by an increase in body weight gain in females, but a decrease in body weight gain and food intake in males. Independent of E. coli treatment, plasma levels of anti-α-MSH and ACTH immunoglobulin (Ig)G were higher in female than male rats. Females responded to E. coli by increasing α-MSH IgG levels and affinity, but males by increasing α-MSH IgM levels. Affinity of IgG for ACTH was increased in both E. coli-treated females and males, although with different kinetics. IgG from females stimulated more efficiently α-MSH-induced cyclic adenosine monophosphate production by melanocortin 4 receptor-expressing cells compared with IgG from males. Sex-related response to how E. coli affects feeding and anti-melanocortin hormone antibody production may depend on the presence of these bacteria in the gut before E. coli supplementation. These data suggest that sex-related presence of certain gut bacteria may represent a risk factor for ED development. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Effect of incubation temperatures for inactivation of Escherichia coli and related bacteria after gamma-irradiation

    International Nuclear Information System (INIS)

    Nakauma, Makoto; Ito, Hitoshi; Tada, Mikiro

    2000-01-01

    Irradiated fresh meat or fishery products have been expected to store and distribute under refrigerated temperature below 10degC. From previous reports, growth of coliform bacteria in these products were suppressed by gamma-irradiation below expected doses obtained at 30-37degC. This research was performed to observe the irradiation effect on the inactivation of Escherichia coli and related bacteria at different incubation temperatures of 10-40degC on plate agar after irradiation. From this study, D10 values of all strains decreased 17- 45% at 10degC compared with maximum D10 values at 30- 40degC. Radiation sensitivities were related to the ability to grow at low temperatures in which psychrotrophic type E. coli A4-1 indicated most sensitive to radiation, next of Salmonella enteritidis YK-2, E. coli S2, B4 whereas most resistant at Enterobacter agglomerans K3-1. (author)

  13. Effect of incubation temperatures for inactivation of Escherichia coli and related bacteria after gamma-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nakauma, Makoto; Ito, Hitoshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Tada, Mikiro [Okayama Univ. (Japan). Faculty of Agriculture

    2000-09-01

    Irradiated fresh meat or fishery products have been expected to store and distribute under refrigerated temperature below 10degC. From previous reports, growth of coliform bacteria in these products were suppressed by gamma-irradiation below expected doses obtained at 30-37degC. This research was performed to observe the irradiation effect on the inactivation of Escherichia coli and related bacteria at different incubation temperatures of 10-40degC on plate agar after irradiation. From this study, D10 values of all strains decreased 17- 45% at 10degC compared with maximum D10 values at 30- 40degC. Radiation sensitivities were related to the ability to grow at low temperatures in which psychrotrophic type E. coli A4-1 indicated most sensitive to radiation, next of Salmonella enteritidis YK-2, E. coli S2, B4 whereas most resistant at Enterobacter agglomerans K3-1. (author)

  14. Study of the effects of high-energy proton beams on escherichia coli

    Science.gov (United States)

    Park, Jeong Chan; Jung, Myung-Hwan

    2015-10-01

    Antibiotic-resistant bacterial infection is one of the most serious risks to public health care today. However, discouragingly, the development of new antibiotics has progressed little over the last decade. There is an urgent need for alternative approaches to treat antibiotic-resistant bacteria. Novel methods, which include photothermal therapy based on gold nano-materials and ionizing radiation such as X-rays and gamma rays, have been reported. Studies of the effects of high-energy proton radiation on bacteria have mainly focused on Bacillus species and its spores. The effect of proton beams on Escherichia coli (E. coli) has been limitedly reported. Escherichia coli is an important biological tool to obtain metabolic and genetic information and is a common model microorganism for studying toxicity and antimicrobial activity. In addition, E. coli is a common bacterium in the intestinal tract of mammals. In this research, the morphological and the physiological changes of E. coli after proton irradiation were investigated. Diluted solutions of cells were used for proton beam radiation. LB agar plates were used to count the number of colonies formed. The growth profile of the cells was monitored by using the optical density at 600 nm. The morphology of the irradiated cells was observed with an optical microscope. A microarray analysis was performed to examine the gene expression changes between irradiated samples and control samples without irradiation. E coli cells have observed to be elongated after proton irradiation with doses ranging from 13 to 93 Gy. Twenty-two were up-regulated more than twofold in proton-irradiated samples (93 Gy) compared with unexposed one.

  15. Computational determination of the effects of virulent Escherichia coli and salmonella bacteriophages on human gut.

    Science.gov (United States)

    Mostafa, Marwa Mostafa; Nassef, Mohammad; Badr, Amr

    2016-10-01

    Salmonella and Escherichia coli are different types of bacteria that cause food poisoning in humans. In the elderly, infants and people with chronic conditions, it is very dangerous if Salmonella or E. coli gets into the bloodstream and then they must be treated by phage therapy. Treating Salmonella and E. coli by phage therapy affects the gut flora. This research paper presents a system for detecting the effects of virulent E. coli and Salmonella bacteriophages on human gut. A method based on Domain-Domain Interactions (DDIs) model is implemented in the proposed system to determine the interactions between the proteins of human gut bacteria and the proteins of bacteriophages that infect virulent E. coli and Salmonella. The system helps gastroenterologists to realize the effect of injecting bacteriophages that infect virulent E. coli and Salmonella on the human gut. By testing the system over Enterobacteria phage 933W, Enterobacteria phage VT2-Sa and Enterobacteria phage P22, it resulted in four interactions between the proteins of the bacteriophages that infect E. coli O157:H7, E. coli O104:H4 and Salmonella typhimurium and the proteins of human gut bacterium strains. Several effects were detected such as: antibacterial activity against a number of bacterial species in human gut, regulation of cellular differentiation and organogenesis during gut, lung, and heart development, ammonia assimilation in bacteria, yeasts, and plants, energizing defense system and its function in the detoxification of lipopolysaccharide, and in the prevention of bacterial translocation in human gut. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Effect of the oyster contaminated in Salmonella typhimurium and Escherichia coli

    International Nuclear Information System (INIS)

    Brena V, M.

    1992-08-01

    In this work the effect of the oyster contaminated in the species of bacteria better studied by its genetic composition these are the Salmonella typhimurium and the Escherichia coli and that its have been starting point for later radiobiological studies in superior organisms. Of this its have arisen two general lines. The research about the genotoxic effect of substances or mixtures in bacteria with the collaboration of the groups of Drosophila and X-ray Fluorescence analysis and on the other hand the study of the low doses of radiation also in bacteria. It is also treated the topic about the genetic effect of aromatic hydrocarbons in different biological systems. (Author)

  17. Antibacterial effect of lactoferricin B on Escherichia coli O157:H7 in ground beef.

    Science.gov (United States)

    Venkitanarayanan, K S; Zhao, T; Doyle, M P

    1999-07-01

    The antibacterial activity of lactoferricin B on enterohemorrhagic Escherichia coli O157:H7 in 1% peptone medium and ground beef was studied at 4 and 10 degrees C. In 1% peptone medium, 50 and 100 microg of lactoferricin B per ml reduced E. coli O157:H7 populations by approximately 0.7 and 2.0 log CFU/ml, respectively. Studies comparing the antibacterial effect of lactoferricin B on E. coli O157:H7 in 1% peptone at pH 5.5 and 7.2 did not reveal any significant difference (P > 0.5) at the two pH values. Lactoferricin B (100 microg/g) reduced E. coli O157:H7 population in ground beef by about 0.8 log CFU/g (P 0.5) was observed in the total plate count between treatment and control ground beef samples stored at 4 and 10 degrees C. The antibacterial effect of lactoferricin B on E. coli O157:H7 observed in this study is not of sufficient magnitude to merit its use in ground beef for controlling the pathogen.

  18. escherichia coli serotypes confirmed in experimental mammary ...

    African Journals Online (AJOL)

    DJFLEX

    VARIATIONS IN VIRULENCE OF THREE (3) ESCHERICHIA COLI. SEROTYPES CONFIRMED IN ... ows are susceptible to E. coli infection because. E. coli exist in the .... Coli infections in mice: A laboratory animal model for research in.

  19. Study of Antibacterial Effect of Novel Thiazole, Imidazole and Tetrahydropyridine Derivatives against Escherichia coli

    Directory of Open Access Journals (Sweden)

    Behzad Ghasemi

    2016-01-01

    Full Text Available > Introduction: Escherichia coli is one of the important pathogens in human with globalimportance. Because of the necessity for identification and the use of novel antibacterialcompounds against E. coli, in this present study we focused on the antibacterial effects ofsynthesized thiazole, imidazole and tetrahydropyridine derivatives on E. coli.Methods: For evaluation of antibacterial effect, the disk diffusion method was applied to measurethe growth inhibition zone diameter and broth micro-dilution was performed to determine theminimum inhibitory concentration (MIC.Results: Assessing the antibacterial effect showed that only 6d derivative of thiazole hadinhibitory effect on E. coli and the other thiazole, imidazole and tetrahydropyridine derivativeslacked any inhibitory result on this organism. The inhibitory effect of 6d derivative of thiazolewas MIC=125 and growth inhibition zone diameter of 16±0.1.Discussion: The antibacterial effect of thiazole, imidazole and tetrahydropyridine derivativesdiffers from each other and chemical linkages such as oxygen to thiazole ring in 6d derivative,could have reinforced this effect. The next step is determination of the toxicity and therapeuticeffects in the laboratory animals.

  20. Antimicrobial resistant Escherichia coli in the municipal wastewater system: effect of hospital effluent and environmental fate.

    Science.gov (United States)

    Harris, Suvi; Morris, Carol; Morris, Dearbhaile; Cormican, Martin; Cummins, Enda

    2014-01-15

    The prevalence of antimicrobial resistant (AMR) bacteria is increasing worldwide and remains a significant medical challenge which may lead to antimicrobial redundancy. The contribution of hospital effluent to the prevalence of resistance in wastewater treatment plant (WWTP) effluents is not fully understood. AMR bacteria contained in hospital effluent may be released into the aquatic and soil environments after WWTP processing. Hence, the objective of this study is to identify the extent hospital effluent contributes to contamination of these environments by comparing two WWTPs, one which receives hospital effluent and one which does not. AMR Escherichia coli were monitored in the two WWTPs. A model was developed using these monitored values to predict the effect of hospital effluent within a WWTP. The model predicted levels of AMR E. coli in the aquatic environment and potential bather exposure to AMR E. coli. The model results were highly variable. WWTP influent containing hospital effluent had a higher mean percentage of AMR E. coli; although, there appeared to be no within treatment plant effect on the prevalence of AMR E. coli. Examination of WWTP sludge showed a similar variation. There appeared to be no consistent effect from the presence of hospital effluent. The human exposure assessment model predicted swimmer intake of AMR E. coli between 6 and 193CFU/100ml sea water. It appears that hospital effluent is not the main contributing factor behind the development and persistence of AMR E. coli within WWTPs, although resistance may be too well-developed to identify an influence from hospital effluent. Mitigation needs to focus on the removal of already present resistant bacteria but for new or hospital specific antimicrobials focus needs to be on their limited release within effluents or separate treatment. © 2013.

  1. Effects of substitutions at position 180 in the Escherichia coli RNA ...

    Indian Academy of Sciences (India)

    Escherichia coli RNA polymerase, two mutant variants of the protein with substitutions for either alanine or glutamic .... promoter signals utilized for in vitro transcription assays and ..... free recombinant protein using a self-cleavable affinity tag.

  2. A simple and effective method for construction of Escherichia coli strains proficient for genome engineering.

    Directory of Open Access Journals (Sweden)

    Young Shin Ryu

    Full Text Available Multiplex genome engineering is a standalone recombineering tool for large-scale programming and accelerated evolution of cells. However, this advanced genome engineering technique has been limited to use in selected bacterial strains. We developed a simple and effective strain-independent method for effective genome engineering in Escherichia coli. The method involves introducing a suicide plasmid carrying the λ Red recombination system into the mutS gene. The suicide plasmid can be excised from the chromosome via selection in the absence of antibiotics, thus allowing transient inactivation of the mismatch repair system during genome engineering. In addition, we developed another suicide plasmid that enables integration of large DNA fragments into the lacZ genomic locus. These features enable this system to be applied in the exploitation of the benefits of genome engineering in synthetic biology, as well as the metabolic engineering of different strains of E. coli.

  3. Effect of free radicals and cultivation media on radiation sensitivities of escherichia coli and related bacteria

    International Nuclear Information System (INIS)

    Ito, Hitoshi

    2000-01-01

    Effects of gamma-irradiation on some strains of Escherichia coli, Salmonella enteritidis and Staphylococcus aureus were investigated in the presence of N 2 , N 2 O and O 2 and with the hydroxyl radical (OH) scavengers glycerol, polyethylene glycerol and formate. Injured cell membrane of bacteria was detected using with MacConkey agar for E. coli and S. enteritidis and 7% NaCl Triptic soy agar for St. aureus instead of Tryptic soy agar for recovery medium. From this study, addition of glycerol significantly reduced the sensitivity in all of strains, and cell membrane was not injured significantly except in radiation sensitive strain E. coli A4-1. When superoxide radicals (O 2 ) were generated during irradiation in the presence of formate, injured cell membrane increased significantly in all of strains. However, molecular oxygen (O 2 ) and OH radicals also had some effects on the damage of cell membrane. These results suggest that most radiation induced cell lethality was responsible to the cooperative effects of intracellular OH radicals and O 2 on DNA with lessor effect of damage on cell membrane by O 2 radicals, O 2 and OH radicals. On the radiation sensitive strain of E. coli, cell lethality occurred significantly by the injury of cell membrane compared with other strains. (author)

  4. Antibacterial Effect of Curcuma longa (Turmeric) Against Staphylococcus aureus and Escherichia coli.

    Science.gov (United States)

    Afrose, R; Saha, S K; Banu, L A; Ahmed, A U; Shahidullah, A S; Gani, A; Sultana, S; Kabir, M R; Ali, M Y

    2015-07-01

    This observational study was conducted during the period from July 2010 to June 2011 in the Department of Pharmacology in the collaboration of Department of Microbiology, Mymensingh Medical College, Mymensingh to determine the profile of antibacterial effect of Crude Turmeric paste aqueous turmeric extract, and standard antibiotic Amikacin against Staphylococcus aureus and Escherichia coli. Three separate experiments were done e.g. (Expt- I) Inhibitory effect of Crude Turmeric paste incorporated into nutrient agar (NA) media, (Expt- II) Minimum inhibitory concentration of (a) Aqueous Turmeric extract and (b) Amikacin by broth dilution technique and (Expt-III) their subculture study in nutrient agar (NA) media for confirmation of respective results of previous experiments. Inhibitory effects were observed against the growth of Staph Aureus and Esch coli at 10% and 30% respectively of Crude Turmeric paste incorporated into NA media. The broth dilution technique was followed to determine the MIC of Aqueous Turmeric extract and Amikacin. The MIC of Aqueous Turmeric extract was 800 μg/ml against Staph aureus and that against Esch coli was 2000 μg/ml and the MIC of Amikacin was 10 μg/ml for both the bacteria. The MIC of Amikacin was the lowest in comparison to MIC of Aqueous Turmeric extract for complete inhibition of growth of Staph aureus and Esch coli. The subculture study showed similar results with that of previous experiments in terms of inhibitory effects of Crude Turmeric paste and MIC of Aqueous Turmeric extract and Amikacin against all of the organisms studied.

  5. Inhibition of electron transfer and uncoupling effects by emodin and emodinanthrone in Escherichia coli.

    Science.gov (United States)

    Ubbink-Kok, T; Anderson, J A; Konings, W N

    1986-07-01

    The anthraquinones emodin (1,3,delta-trihydroxy-6-methylanthraquinone) and emodinanthrone (1,3,8-trihydroxy-6-methylanthrone) inhibited respiration-driven solute transport at micromolar concentrations in membrane vesicles of Escherichia coli. This inhibition was enhanced by Ca ions. The inhibitory action on solute transport is caused by inhibition of electron flow in the respiratory chain, most likely at the level between ubiquinone and cytochrome b, and by dissipation of the proton motive force. The uncoupling action was confirmed by studies on the proton motive force in beef heart cytochrome oxidase proteoliposomes. These two effects on energy transduction in cytoplasmic membranes explain the antibiotic properties of emodin and emodinanthrone.

  6. Synergistic effect of eugenol with Colistin against clinical isolated Colistin-resistant Escherichia coli strains

    Directory of Open Access Journals (Sweden)

    Yi-ming Wang

    2018-01-01

    Full Text Available Abstract Background Bacterial infections have become more challenging to treat due to the emergence of multidrug-resistant pathogenic bacteria. Combined antibiotics prove to be a relatively effective method to control such resistant strains. This study aim to investigate synergistic activity of eugenol combined with colistin against a collection of clinical isolated Escherichia coli (E.coli strains, and to evaluate potential interaction. Methods Antimicrobial susceptibility, minimum inhibitory concentration (MIC and fractional inhibitory concentration index (FICI of the bacteria were determined by disk diffusion assay, broth microdilution method and checkerboard assay, respectively. The mcr-1 mRNA expression was measured by Real-time PCR. To predict possible interactions between eugenol and MCR-1, molecular docking assay was taken. Results For total fourteen strains including eight colistin-resistant strains, eugenol was determined with MIC values of 4 to 8 μg/mL. Checkerboard dilution test suggested that eugenol exhibited synergistic activity when combined with colistin (FICI ranging from 0.375 to 0.625. Comparison analysis of Real-time PCR showed that synergy could significantly down-regulate expression of mcr-1 gene. A metal ion coordination bond with catalytic zinc atom and a hydrogen bond with crucial amino acid residue Ser284 of MCR-1 were observed after molecular docking, indicating antibacterial activity and direct molecular interactions of eugenol with MCR-1 protein. Conclusions Our results demonstrated that eugenol exhibited synergistic effect with colistin and enhanced its antimicrobial activity. This might further contribute to the antibacterial actions against colistin-resistant E.coli strains. Graphical abstract Synergistic effect of eugenol with colistin against colistin-resistant Escherichia coli isolates.

  7. Effect of heat treatment on the survival of Escherichia Coli O157:H7 ...

    African Journals Online (AJOL)

    The survival of Escherichia coli O157:H7 in raw milk treated in experimental pasteurizer was investigated in the year 2010. Raw milk was inoculated with different initial concentrations of E. coli O157:H7 and heated for 15 seconds at temperatures ranging from 69OC to 73OC. E. coli O157:H7 cells were not isolated from the ...

  8. Effects of Escherichia coli on mixotrophic growth of Chlorella minutissima and production of biofuel precursors.

    Directory of Open Access Journals (Sweden)

    Brendan T Higgins

    Full Text Available Chlorella minutissima was co-cultured with Escherichia coli in airlift reactors under mixotrophic conditions (glucose, glycerol, and acetate substrates to determine possible effects of bacterial contamination on algal biofuel production. It was hypothesized that E. coli would compete with C. minutissima for nutrients, displacing algal biomass. However, C. minutissima grew more rapidly and to higher densities in the presence of E. coli, suggesting a symbiotic relationship between the organisms. At an initial 1% substrate concentration, the co-culture produced 200-587% more algal biomass than the axenic C. minutissima cultures. Co-cultures grown on 1% substrate consumed 23-737% more of the available carbon substrate than the sum of substrate consumed by E. coli and C. minutissima alone. At 1% substrate, total lipid and starch productivity were elevated in co-cultures compared to axenic cultures indicating that bacterial contamination was not detrimental to the production of biofuel precursors in this specific case. Bio-fouling of the reactors observed in co-cultures and acid formation in all mixotrophic cultures, however, could present challenges for scale-up.

  9. Effects of paraquat on Escherichia coli: Differences between B and K-12 strains

    International Nuclear Information System (INIS)

    Kitzler, J.W.; Minakami, H.; Fridovich, I.

    1990-01-01

    Escherichia coli B and K-12 are equally susceptible to the bacteriostatic effects of aerobic paraquat, but they differed strikingly when the lethality of paraquat was evaluated. E. coli B suffered an apparent loss of viability when briefly exposed to paraquat, whereas E. coli K-12 did not. This difference depended on the ability of the B-strain, but not the K-12 strain, to retain internalized paraquat; the B strain was killed on aerobic tryptic soy-yeast extract plates during the incubation which preceded the counting of colonies. This difference in retention of paraquat between strains was demonstrated by delayed loss of viability, by growth inhibition, and by cyanide-resistant respiration after brief exposure to paraquat, washing, and testing in fresh medium. This difference was also shown by using [ 14 C]paraquat. This previously unrecognized difference between E. coli B and K-12 has been the cause of apparently contradictory reports and should lead to some reevaluation of the pertinent literature

  10. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Nielsen, E.M.; Klemm, Per

    2006-01-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast...... 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...

  11. 76 FR 20542 - Escherichia coli

    Science.gov (United States)

    2011-04-13

    ... beef, Escherichia coli and coliphages were found in chicken, fresh pork, fresh oyster, fresh mushrooms, lettuce, chicken pot pie, biscuit dough, deli loaf, deli roasted turkey, and package roasted chicken... surfaces, and in foods such as ground beef, pork sausage, chicken, oysters, cheese, fresh mushrooms, and...

  12. Conjugal Pairing in Escherichia Coli

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 13; Issue 8. Conjugal Pairing in Escherichia Coli. Joshua Lederberg. Classics Volume 13 Issue 8 August 2008 pp 793-794. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/013/08/0793-0794 ...

  13. Escherichia coli as a probiotic?

    NARCIS (Netherlands)

    Jansen, GJ; Wildeboer-Veloo, ACM; van der Waaij, D; Degener, JE

    1998-01-01

    The influence of oral treatment with a suspension of non-pathogenic Escherichia coli cells (commercially available as: Symbioflor II(R)) on the morphological composition of the gut microflora and on the systemic humoral immune response (the IgG-, IgA- and IgM-isotype) against the bacterial cells in

  14. Dichromatic laser radiation effects on DNA of Escherichia coli and plasmids

    Science.gov (United States)

    Martins, W. A.; Polignano, G. A. C.; Guimarães, O. R.; Geller, M.; Paoli, F.; Fonseca, A. S.

    2015-04-01

    Dichromatic and consecutive laser radiations have attracted increased attention for clinical applications as offering new tools for the treatment of dysfunctional tissues in situations where monochromatic radiation is not effective. This work evaluated the survival, filamentation and morphology of Escherichia coli cells, and the induction of DNA lesions, in plasmid DNA exposed to low-intensity consecutive dichromatic laser radiation. Exponential and stationary wild type and formamidopyrimidine DNA glycosylase/MutM protein deficient E. coli cultures were exposed to consecutive low-intensity dichromatic laser radiation (infrared laser immediately after red laser) to study the survival, filamentation and morphology of bacterial cells. Plasmid DNA samples were exposed to dichromatic radiation to study DNA lesions by electrophoretic profile. Dichromatic laser radiation affects the survival, filamentation and morphology of E. coli cultures depending on the growth phase and the functional repair mechanism of oxidizing lesions in DNA, but does not induce single/double strands breaks or alkali-labile DNA lesions. Results show that low-intensity consecutive dichromatic laser radiation induces biological effects that differ from those induced by monochromatic laser radiation, suggesting that other therapeutic effects could be obtained using dichromatic radiation.

  15. Low-intensity red and infrared laser effects at high fluences on Escherichia coli cultures

    Energy Technology Data Exchange (ETDEWEB)

    Barboza, L.L.; Campos, V.M.A.; Magalhaes, L.A.G. [Instituto de Biologia Roberto Alcantara Gomes, Rio de Janeiro, RJ (Brazil). Departamento de Biofisica e Biometria; Paoli, F. [Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, MG (Brazil). Departamento de Morfologia; Fonseca, A.S., E-mail: adnfonseca@ig.com.br [Universidade Federal do Estado do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Departamento de Ciencias Fisiologicas

    2015-10-15

    Semiconductor laser devices are readily available and practical radiation sources providing wavelength tenability and high monochromaticity. Low-intensity red and near-infrared lasers are considered safe for use in clinical applications. However, adverse effects can occur via free radical generation, and the biological effects of these lasers from unusually high fluences or high doses have not yet been evaluated. Here, we evaluated the survival, filamentation induction and morphology of Escherichia coli cells deficient in repair of oxidative DNA lesions when exposed to low-intensity red and infrared lasers at unusually high fluences. Cultures of wild-type (AB1157), endonuclease III-deficient (JW1625-1), and endonuclease IV-deficient (JW2146-1) E. coli, in exponential and stationary growth phases, were exposed to red and infrared lasers (0, 250, 500, and 1000 J/cm{sup 2}) to evaluate their survival rates, filamentation phenotype induction and cell morphologies. The results showed that low-intensity red and infrared lasers at high fluences are lethal, induce a filamentation phenotype, and alter the morphology of the E. coli cells. Low-intensity red and infrared lasers have potential to induce adverse effects on cells, whether used at unusually high fluences, or at high doses. Hence, there is a need to reinforce the importance of accurate dosimetry in therapeutic protocols. (author)

  16. Effect of carvacrol on O157 and non-O157 Shiga toxin producing Escherichia coli

    Directory of Open Access Journals (Sweden)

    Alexandros Stratakos

    2017-06-01

    Full Text Available Shiga toxin Escherichia coli (STEC strains are important foodborne bacteria linked to diarrhea, enteritis, hemolytic-uremic syndrome and in some cases death. E. coli O157:H7 is the most common strain amongst STECs however non-O157 STECs have been connected with several outbreaks on an international level.  The use of natural plant extracts to reduce the risk from foodborne pathogens is gaining increasing importance. Therefore in this study, we tested the antibacterial effect of carvacrol, a major component of oregano essential oil, on E. coli serogroups O157, O26, O45, O103, O111, O121, O145 as well as serogroup O104 responsible for the massive outbreak in Germany in 2011. Carvacrol showed antibacterial effect on all strains tested. The relative electric conductivity was assessed in order to investigate the changes in membrane permeability and thus to investigate the antimicrobial mechanism of carvacrol. Results showed that the relative conductivity increased with increasing concentrations of carvacrol which showed that there was an increasing leakage of electrolytes due to disruption of the cell membrane. The data presented here revealed that carvacrol has the potential to be used as a natural antimicrobial against STECs.

  17. Effect of millimeter waves on survival of UVC-exposed Escherichia coli

    International Nuclear Information System (INIS)

    Rojavin, M.A.; Ziskin, M.C.

    1995-01-01

    Bacterial cells of the strain Escherichia coli K12 were exposed to millimeter electromagnetic waves (mm waves) with and without additional exposure to ultraviolet light λ = 254 nm (UVC). The mm waves were produced by a medical microwave generator emitting a 4-GHz-wide band around a 61 GHz center frequency and delivering an irradiation of 1mW/cm 2 and a standard absorption rate (SAR) of 84 W/kg to the bacteria. Exposure to the mm waves alone for up to 30 minutes did not change the survival rate of bacteria. Exposure to mm waves followed by UVC irradiation also did not alter the number of surviving E. coli cells in comparison to UVC-treated controls. When mm waves were applied after the UVC exposure, a dose-dependent increase of up to 30% in the survival of E. coli was observed compared to UVC + sham-irradiated bacteria. Because sham controls and experimental samples were maintained under the same thermal conditions, the effect is not likely to be due to heating, although the possibility of nonuniform distribution of microwave heating in different layers of irradiated bacterial suspension cannot be ruled out. The mechanism for this effect appears to involve certain DNA repair systems that act as cellular targets for mm waves

  18. Irradiation effect of escherichia coli O157 : H7 in meats

    International Nuclear Information System (INIS)

    Ito, Hitoshi; Harsojo

    1998-01-01

    Escherichia coli O157 : H7 is a rapidly emerging food-born pathogen which has been linked to outbreaks of hemorrhagic diarrhea in Japan, USA or many European countries. From this study, two strains of E. coli O157 : H7 were isolated from beef and chicken meats in each one sample of 4 replicates. Some of the biochemical characteristics of these isolates were different from type strain IID959. These isolates could grow quickly at 10degC on cultivation of nutrient agar. D 10 value of these isolates were obtained to be 0.06kGy in 0.067M phosphate buffer suspension which were highly sensitive than D 10 value of 0.12kGy on type strain IID959. On the irradiation effect of type strain IID959 in ground beef, D 10 value was obtained as 0.26kGy at fresh condition and 0.46kGy at frozen condition, respectively. From these results, necessary dose for elimination of E. coli O157 : H7 was decided as 1.5kGy for fresh meats and 3kGy for frozen meats. (author)

  19. Effects of simulated Mars conditions on the survival and growth of Escherichia coli and Serratia liquefaciens.

    Science.gov (United States)

    Berry, Bonnie J; Jenkins, David G; Schuerger, Andrew C

    2010-04-01

    Escherichia coli and Serratia liquefaciens, two bacterial spacecraft contaminants known to replicate under low atmospheric pressures of 2.5 kPa, were tested for growth and survival under simulated Mars conditions. Environmental stresses of high salinity, low temperature, and low pressure were screened alone and in combination for effects on bacterial survival and replication, and then cells were tested in Mars analog soils under simulated Mars conditions. Survival and replication of E. coli and S. liquefaciens cells in liquid medium were evaluated for 7 days under low temperatures (5, 10, 20, or 30 degrees C) with increasing concentrations (0, 5, 10, or 20%) of three salts (MgCl(2), MgSO(4), NaCl) reported to be present on the surface of Mars. Moderate to high growth rates were observed for E. coli and S. liquefaciens at 30 or 20 degrees C and in solutions with 0 or 5% salts. In contrast, cell densities of both species generally did not increase above initial inoculum levels under the highest salt concentrations (10 and 20%) and the four temperatures tested, with the exception that moderately higher cell densities were observed for both species at 10% MgSO(4) maintained at 20 or 30 degrees C. Growth rates of E. coli and S. liquefaciens in low salt concentrations were robust under all pressures (2.5, 10, or 101.3 kPa), exhibiting a general increase of up to 2.5 orders of magnitude above the initial inoculum levels of the assays. Vegetative E. coli cells were maintained in a Mars analog soil for 7 days under simulated Mars conditions that included temperatures between 20 and -50 degrees C for a day/night diurnal period, UVC irradiation (200 to 280 nm) at 3.6 W m(-2) for daytime operations (8 h), pressures held at a constant 0.71 kPa, and a gas composition that included the top five gases found in the martian atmosphere. Cell densities of E. coli failed to increase under simulated Mars conditions, and survival was reduced 1 to 2 orders of magnitude by the interactive

  20. Effects of aging on endotoxin tolerance induced by lipopolysaccharides derived from Porphyromonas gingivalis and Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Ying Sun

    Full Text Available Periodontitis is a bacterially induced chronic inflammatory disease. Exposure of the host to periodontal pathogens and their virulence factors induces a state of hyporesponsiveness to subsequent stimulations, termed endotoxin tolerance. Aging has a profound effect on immune response to bacteria challenge. The aim of this study was to explore the effects of aging on endotoxin tolerance induced by Porphyromonas gingivalis (P. gingivalis lipopolysaccharide (LPS and Escherichia coli (E. coli LPS in murine peritoneal macrophages.We studied the cytokine production (TNF-α and IL-10 and Toll-like receptor 2, 4 (TLR2, 4 gene and protein expressions in peritoneal macrophages from young (2-month-old and middle-aged (12-month-old ICR mice following single or repeated P. gingivalis LPS or E. coli LPS stimulation. Pretreatment of peritoneal macrophages with P. gingivalis LPS or E. coli LPS resulted in a reduction in TNF-α production and an increase in IL-10 production upon secondary stimulation (p<0.05, and the markedly lower levels of TNF-α and higher levels of IL-10 were observed in macrophages from young mice compared with those from middle-aged mice (p<0.05. In addition, LPS restimulations also led to the significantly lower expression levels of TLR2, 4 mRNA and protein in macrophages from young mice (p<0.05.Repeated LPS stimulations triggered endotoxin tolerance in peritoneal macrophages and the ability to develop tolerance in young mice was more excellent. The impaired ability to develop endotoxin tolerance resulted from aging might be related to TLR2, 4 and might lead to the incontrollable periodontal inflammation in older adults.

  1. Effect of carprofen treatment following experimentally induced Escherichia coli mastitis in primiparous cows.

    Science.gov (United States)

    Vangroenweghe, F; Duchateau, L; Boutet, P; Lekeux, P; Rainard, P; Paape, M J; Burvenich, C

    2005-07-01

    Acute Escherichia coli mastitis is one of the major sources of economic loss in the dairy industry due to reduced milk production, treatment costs, discarded milk, and occasional fatal disease. Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used as adjunctive therapy to antibiotics. The objective of the current study was to evaluate the effect of carprofen treatment following infusion of Escherichia coli into the mammary glands of primiparous cows during the periparturient period. Severity of mastitis was scored based on the average milk production in the uninfected quarters on d +2 postinoculation and a clinical severity score. Carprofen was administered intravenously at 9 h postchallenge, when clinical signs of mastitis appeared. In previous work, efficacy of NSAIDs was mainly evaluated using clinical symptoms. In the present study, the effect of carprofen on innate immune response was also assessed by quantification of inflammatory mediators. All primiparous cows reacted as moderate responders throughout the experimental period. Primiparous cows were intramammarily inoculated with 1 x 10(4) cfu of E. coli P4:O32 in 2 left quarters. Analysis of blood and milk parameters, including IL-8, complement component C5a, lipopolysaccharide-binding protein (LBP), soluble CD14, prostaglandin E2, and thromboxane B2 was performed from d 0 to d +6 relative to intramammary inoculation. Rectal temperature in carprofen-treated animals was lower than in control animals at 3 and 6 h posttreatment. Treatment also restored the decreased reticulorumen motility that occurs during E. coli mastitis to preinfection levels faster than in control animals. Carprofen treatment resulted in an earlier normalization of the clinical severity score. Eicosanoid (prostaglandin E2 and thromboxane B2) production in milk tended to be inhibited by carprofen. No significant differences in the kinetic patterns of somatic cell count, IL-8, complement component C5a, LBP, and soluble CD14 were

  2. Inhibition of Escherichia Coli, Salmonella and Staphylococcus ...

    African Journals Online (AJOL)

    Escherichia coli O157:H7, Salmonella typhimurium and Staphylococcus. aureus are of great concern to the food industry, especially in foods stored under refrigerated conditions where, unlike most food-borne pathogens are able to multiply. This investigation was conducted to study the inhibitory effect of some spice ...

  3. Simulating Escherichia coli O157:H7 transmission to assess effectiveness of interventions in Dutch dairy-beef slaughterhouses

    NARCIS (Netherlands)

    Vosough Ahmadi, B.; Velthuis, A.G.J.; Hogeveen, H.; Huirne, R.B.M.

    2006-01-01

    Beef contamination with Escherichia coli O157:H7 (VTEC) is an important food-safety issue. To investigate the effectiveness of interventions against VTEC in Dutch beef industrial slaughterhouses that slaughter 500 dairy cattle per day, a Monte Carlo simulation model was built. We examined seven

  4. Antimicrobial effect of sour pomegranate sauce on Escherichia coli O157:H7 and Staphylococcus aureus.

    Science.gov (United States)

    Kışla, Duygu; Karabıyıklı, Şeniz

    2013-05-01

    Pomegranate sauce is one of the most popular pomegranate products produced in Turkey. This study was conducted to determine the minimum inhibitory concentrations (MICs) of both traditional and commercial sour pomegranate sauce samples on Staphylococcus aureus (ATCC 25923) and Escherichia coli O157:H7 (ATCC 43895). The initial microflora of the pomegranate sauce samples was determined by performing the enumerations of total aerobic mesophilic bacteria, yeast and mold, S. aureus, E. coli, and the determination of Salmonella spp. MIC tests were applied to the neutralized and the original (unneutralized) sour pomegranate sauce samples in order to put forth the inhibition effect depending on low pH value. It was found that inhibitory effect of the traditional and the commercial samples, except one sample, on pathogens was not only due to the acidity of the products. The results of MIC tests indicated that although both traditional and commercial samples showed a considerable inhibitory effect on test microorganisms, the traditional pomegranate sauce samples were more effective than the commercial ones. © 2013 Institute of Food Technologists®

  5. Effects of chlortetracycline and copper supplementation on antimicrobial resistance of fecal Escherichia coli from weaned pigs.

    Science.gov (United States)

    Agga, G E; Scott, H M; Amachawadi, R G; Nagaraja, T G; Vinasco, J; Bai, J; Norby, B; Renter, D G; Dritz, S S; Nelssen, J L; Tokach, M D

    2014-06-01

    Feed-grade chlortetracycline (CTC) and copper are both widely utilized in U.S. pig production. Cluster randomized experiment was conducted to evaluate the effects of CTC and copper supplementation in weaned pigs on antimicrobial resistance (AMR) among fecal Escherichia coli. Four treatment groups: control, copper, CTC, or copper plus CTC were randomly allocated to 32 pens with five pigs per pen. Fecal samples were collected weekly from three pigs per pen for six weeks. Two E. coli isolates per fecal sample were tested for phenotypic and genotypic resistance against antibiotics and copper. Data were analyzed with multilevel mixed effects logistic regression, multivariate probit analysis and discrete time survival analysis. CTC-supplementation was significantly (99% [95% CI=98-100%]) associated with increased tetracycline resistance compared to the control group (95% [95% CI=94-97%]). Copper supplementation was associated with decreased resistance to most of the antibiotics tested, including cephalosporins, over the treatment period. Overall, 91% of the E. coli isolates were multidrug resistant (MDR) (resistant to ≥3 antimicrobial classes). tetA and blaCMY-2 genes were positively associated (PpcoD were negatively associated with MDR. tetA and blaCMY-2 were positively associated with each other and in turn, these were negatively associated with both tetB and pcoD genes; which were also positively associated with one another. Copper minimum inhibitory concentration was not affected by copper supplementation or by pcoD gene carriage. CTC supplementation was significantly associated with increased susceptibilities of E. coli to copper (HR=7 [95% CI=2.5-19.5]) during treatment period. In conclusion, E. coli isolates from the nursery pigs exhibited high levels of antibiotic resistance, with diverse multi-resistant phenotypic profiles. The roles of copper supplementation in pig production, and pco-mediated copper resistance among E. coli in particular, need to be further

  6. Inhibitory effect of 2‑mercaptoethane sulfonate on the formation of Escherichia coli biofilms in vitro.

    Science.gov (United States)

    Chen, Sheng; He, Nianhai; Yu, Jialin; Li, Luquan; Sun, Fengjun; Hu, Ying; Deng, Rui; Zhong, Shiming; Shen, Leilei

    2015-10-01

    The biofilms (BF) formed by Escherichia coli (E. coli) is an important cause of chronic and recurrent infections due to its capacity to persist on medical surfaces and indwelling devices, demonstrating the importance of inhibiting the formation of E. coli BF and reducing BF infection. Although 2‑mercaptoethane sulfonate (MESNA) exhibits a marked mucolytic effect clinically, the effect of MESNA on the inhibition of E. coli BF formation remains to be elucidated. The present study investigated whether MESNA inhibits the formation of E. coli BF in vitro. The minimum inhibitory concentration of MESNA on E. coli was determined to be 10 mg/ml. Subsequently, the effect of MESNA on BF early adhesion, extracellular polysaccharide (EPS) and extracellular protein were detected. The effect of a subinhibitory concentration of MESNA on BF formation was evaluated, and the inhibitory potency of MESNA against matured BF was assayed. The results revealed that MESNA inhibited early stage adhesion and formation of the E. coli BF, destroyed the mature BF membrane and reduced the EPS and extracellular proteins levels of the BF. In addition, the present study investigated the effects of MESNA on the expression of EPS‑ and adhesion protein‑associated genes using quantitative polymerase chain reaction analysis, which demonstrated that MESNA effectively inhibited the expression of these genes. These results suggested that MESNA possesses anti‑BF formation capability on E. coli in vitro and may be used as a potential reagent for the clinical treatment of E. coli BF‑associated infections.

  7. Effect of gamma irradiation on the sensitivities of escherichia coli at deep frozen conditions

    International Nuclear Information System (INIS)

    Takigami, Machiko; Ito, Hitoshi

    1996-01-01

    Phosphate buffer suspensions of three strains of Escherichia coli were irradiated with gamma-rays at room temperature and deep frozen conditions. They were inoculated on MacConkey agar plates to see the comparative sensitivities to the irradiation. Compared to the irradiation at room temperature, the sensitivities of the strains decreased by irradiation at deep frozen conditions. Addition of glycerol to the E. coli suspensions decreased the sensitivities of E. coli to gamma-rays not only at room temperature but also at deep frozen conditions. These phenomena were elucidated by the decrease of production and mobility of OH radicals at deep frozen conditions. (author)

  8. Effect of Thymine Starvation on Messenger Ribonucleic Acid Synthesis in Escherichia coli

    Science.gov (United States)

    Luzzati, Denise

    1966-01-01

    Luzzati, Denise (Institut de Biologie Physico-Chimique, Paris, France). Effect of thymine starvation on messenger ribonucleic acid synthesis in Escherichia coli. J. Bacteriol. 92:1435–1446. 1966.—During the course of thymine starvation, the rate of synthesis of messenger ribonucleic acid (mRNA, the rapidly labeled fraction of the RNA which decays in the presence of dinitrophenol or which hybridizes with deoxyribonucleic acid) decreases exponentially, in parallel with the viability of the thymine-starved bacteria. The ability of cell-free extracts of starved bacteria to incorporate ribonucleoside triphosphates into RNA was determined; it was found to be inferior to that of extracts from control cells. The analysis of the properties of cell-free extracts of starved cells shows that their decreased RNA polymerase activity is the consequence of a modification of their deoxyribonucleic acid, the ability of which to serve as a template for RNA polymerase decreases during starvation. PMID:5332402

  9. The study of Antimicrobial and Anti-adhesive effect of ProbioticLactobacilli on Uropathogenic Escherichia coli (UPEC

    Directory of Open Access Journals (Sweden)

    Mahsa Sadri

    2016-06-01

    Full Text Available Introduction: One of the most important factors in Urinary Tract Infection caused by Uropathogenic Escherichia coli, is the attachment of bacteria to the host cell surface. Thus, inhibition of bacterial attachment is the appropriate action to prevent infection. The aim of this study was to investigate the antimicrobial and especially anti adhesive characteristics of probiotic bacteria against Escherichia coli by using microbial techniques. Materials and methods: In this study two strains of Lactobacillus acidophilus PTCC 1643 and Lactobacillus casei PTCC 1608 were used .40 Uropathogenic Escherichia coli were collected from Semnan province hospitals.20 samples with the more capability of biofilm production were selected for microbial tests. To evaluate the antimicrobial activity of complete culture and supernatant of probiotic lactobacilli, modified double layer method and dilution of supernatant were used, respectively. The mechanism of co- aggregation of lactobacilli with pathogens was examined. The microtitre plate method was used to detect anti-adhesive activity of Lactobacilli supernatant. Results: The antimicrobial and anti-adhesive effects of probiotic lactobacilli on Uropathogenic Escherichia coli were confirmed in all tests. In this study, Lactobacillus casie with the growth inhibitory (42/7 mm and anti-adhesive (46/7mm effects were reported as a proper probiotic bacterium. Discussion and conclusion: According to the results, the probiotic lactobacilli have spectacular effects to prevent attachment, biofilm formation and pathogenicity of UPEC, so using them to prevent and treat Urinary tract infection is a practical, reasonable and acceptable method.

  10. Experimental electromagnetic effects on the model organism Escherichia coli and the bacteriophage T4

    Science.gov (United States)

    Lisiewski, Darlene Mildred

    This experimentally-based work was designed to answer the research question as to whether the phenomenon of nuclear magnetic resonance (NMR) can produce observable effects upon the bacterial virus activity of T4, with such activity demonstrated through the infection of its host bacterium Escherichia coli. The biological samples were placed for three hours within a coil antenna assembly propagating oscillating fields of radio frequency electromagnetic energy generated at the frequency of 5.6 MHz, and set at right angles within a magnetic field of 1450 gauss (recognizing such conditions are not set for the maximum effective resonance for hydrogen nuclei). The laboratory technique of plaque formation was the basis upon which the statistically tested data were compiled. Exposure of the bacterium alone exhibited an increase in viral activity over the control group (40--68% higher numbers of plaque formation), while exposure of T4 alone saw a decrease (approximately 23%) in infection rates. Depending on the protocol, placement of both T4 and E. coli into the coil assembly saw a decrease of either approximately 50% or 42% in infection rates. Future research must address identification of the effects being observed.

  11. Effect of L-glutamine levels in piglets diets challenged with Escherichia coli lipopolysacharides

    Directory of Open Access Journals (Sweden)

    Arturo Pardo L.

    2014-09-01

    Full Text Available Objective. To evaluate the effect of different levels of L-glutamine on weaned and immunologically challenged piglets with Escherichia coli lipopolysaccharides (LPS on performance parameters, serum cortisol and defense cells. Materials and methods. Four levels of L –glutamine were evaluated (0, 1.0, 1.5, 2.0% as well as the addition, or no addition, of LPS (0.3μg. 96 piglets were used (48 castrated males and 48 females of Agroceres x PenArlan lineage, with an initial age of 21 days and 6.06±0.852 kg live weight. An experimental design was used on randomized blocks in a factorial setting 4 x 2 (levels of L- glutamine with or without challenge. Results. Cubic effect was shown for daily weight gain of unchallenged animals, and was better with the addition of 0.41% L- glutamine. Feed conversion improved with increased levels of L -glutamine for challenged animals. In the evaluation of defense cells, there was interaction of leukocytes with the levels of L- glutamine and the immune challenge. Eosinophils and lymphocytes showed a quadratic effect for the levels of L –glutamine, with a maximum value of 1.30% and 0.5%, respectively. Conclusions. L -glutamine supplementation of up to 2% in the diet improves feed conversion and favors the immune serum of weaned piglets challenged with LPS of E. coli.

  12. Effect of a static magnetic field on Escherichia coli adhesion and orientation

    Czech Academy of Sciences Publication Activity Database

    Mhamdi, L.; Mhamdi, N.; Mhamdi, Nc.; Lejeune, M.; Jaffrezic, N.; Burais, N.; Scorretti, R.; Pokorný, Jiří; Ponsonnet, L.

    2016-01-01

    Roč. 62, č. 11 (2016), s. 944-952 ISSN 0008-4166 Institutional support: RVO:67985882 Keywords : Fluorescence microscopy * Static magnetic field * Escherichia coli Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.462, year: 2016

  13. Effect of Helicobacter pylori Infection on Symptoms of Gastroenteritis Due to Enteropathogenic Escherichia coli in Adults

    NARCIS (Netherlands)

    Chang, Alicia Hsin-Ming; Haggerty, Thomas Dean; de Martel, Catherine; Leung, Cynthia Wai-Mun; Parsonnet, Julie

    Helicobacter pylori can cause hypochlorhydria in some hosts and predispose to diarrheal infections. We tested the hypothesis that chronic H. pylori infection increases the risk of diarrheal illness due to an acid-sensitive organism: enteropathogenic Escherichia coli (EPEC). After testing healthy

  14. Effects of low-frequency magnetic fields on bacteria Escherichia coli

    Czech Academy of Sciences Publication Activity Database

    Strašák, Luděk; Vetterl, Vladimír; Šmarda, J.

    2002-01-01

    Roč. 55, 1/2 (2002), s. 161-164 ISSN 1567-5394 R&D Projects: GA ČR GA310/01/0816; GA AV ČR IBS5004107 Institutional research plan: CEZ:AV0Z5004920 Keywords : ELF magnetic fields * Escherichia coli * exposure Subject RIV: BO - Biophysics Impact factor: 1.463, year: 2002

  15. Protective effect of oral administration of transgenic tobacco seeds against verocytotoxic Escherichia coli strain in piglets.

    Science.gov (United States)

    Rossi, Luciana; Dell'Orto, Vittorio; Vagni, Simona; Sala, Vittorio; Reggi, Serena; Baldi, Antonella

    2014-03-01

    The use of transgenic plants as delivery system for antigenic proteins is attractive for its simplicity and increases likelihood for local immune response at sites of infection. The aim of this study was to evaluate the protective effect of oral administration of tobacco seeds, expressing the FedA, the major protein of the F18 adhesive fimbriae, and B subunit of verocytotoxin, against verocytotoxin-producing E. coli (VTEC) strain in piglets. Forty-three early weaned piglets, were randomly divided into 4 experimental groups: 3 test groups and a control. Treatment groups orally received a bolus, with different dose of tobacco seeds on 0, 1, 2, 14 days post primary administration. After challenge, with 1*10(10) CFU of O138 Escherichia coli strain, piglets showed clinical scores significantly higher in the control group compared to orally immunized groups (P administration of recombinant tobacco seeds expressing antigenic proteins against VTEC strains can induce a protective effect against challenger strain in piglets.

  16. Effectiveness of castor oil extract on Escherichia coli and its endotoxins in root canals.

    Science.gov (United States)

    Valera, Marcia Carneiro; Maekawa, Lilian Eiko; Chung, Adriana; de Oliveira, Luciane Dias; Carvalho, Claudio Antonio Talge; Koga-Ito, Cristiane Yumi; Jorge, Antonio Olavo Cardoso

    2012-01-01

    This in vitro study sought to evaluate the effectiveness of castor oil extract used as an irrigating solution on Escherichia coli and its endotoxins in root canals. Sixty single-rooted teeth were prepared (using castor oil extract as irrigating solution) and divided into five groups (n = 12): Group 1 samples were treated with calcium hydroxide (Ca(OH)2), Group 2 samples were treated with polymyxin B, Group 3 samples were treated with Ca(OH)2 and 2% chlorhexidine gel (CHX), and Group 4 samples were treated with castor oil extract. A control group used physiological saline solution as an irrigant. Canal content samples were collected at four different times: immediately after instrumentation, seven days after instrumentation, after 14 days of intracanal medication, and seven days after removal of intracanal medication. A plating method was used to assess antimicrobial activity and the quantification of endotoxins was evaluated by the chromogenic Limulus lysate assay. Data were submitted to ANOVA and a Dunn test (a = 5%). Irrigation with castor oil extract decreased E. coli counts but had no effect on the level of endotoxins. Samples taken seven days after removal of medication revealed a significant reduction in endotoxin levels in Groups 3 and 4. Compared to the saline solution irrigation, castor oil extract decreased microorganism counts in root canals immediately after canal preparation. None of the medications used completely eliminated endotoxins in the root canal.

  17. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

    International Nuclear Information System (INIS)

    Canuto, K.S.; Guimaraes, O.R.; Geller, M.; Sergio, L.P.S.; Paoli, F.; Fonseca, A.S.

    2015-01-01

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia coli cells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficient E. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out. (author)

  18. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

    Energy Technology Data Exchange (ETDEWEB)

    Canuto, K.S.; Guimaraes, O.R.; Geller, M. [Centro Universitario Serra dos Orgaos, Teresopolis, RJ (Brazil). Centro de Ciencias da Saude; Sergio, L.P.S. [Instituto de Biologia Roberto Alcantara Gomes, Rio de Janeiro, RJ (Brazil). Departamento de Biofisica e Biometria; Paoli, F. [Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, MG (Brazil). Departamento de Morfologia; Fonseca, A.S., E-mail: adnfonseca@ig.com.br [Universidade Federal do Estado do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Departamento de Ciencias Fisiologicas

    2015-10-15

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia coli cells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficient E. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out. (author)

  19. Photoreactivating enzyme from Escherichia coli

    International Nuclear Information System (INIS)

    Snapka, R.M.; Fuselier, C.O.

    1977-01-01

    Escherichia coli photoreactivating enzyme (PRE) has been purified in large amounts from an E.coli strain lysogenic for a defective lambda bacteriophage carrying the phr gene. The resulting enzyme had a pH optimum of 7.2 and an ionic strength optimum of 0.18. It consisted of an apoprotein and cofactor, both of which were necessary for catalytic activity. The apoprotein had a monomer molecular weight of 35,200 and showed stable aggregates under denaturing conditions. The amino acid analysis of the E.coli enzyme was very similar to that of the photoreactivating enzyme from orchid seedlings (Cattelya aurantiaca). Both had arginine at the amino terminus. The cofactor, like the holoenzyme, showed absorption, magnetic circular dichroism, and emission properties indicative of an adenine moiety. Although the isolated enzyme had an action spectrum which peaked at about 360 nm, neither the cofactor, apoenzyme nor holoenzyme showed any detectable absorption between 300 and 400 nm. (author)

  20. Photoreactivating enzyme from Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Snapka, R M; Fuselier, C O [California Univ., Irvine (USA)

    1977-05-01

    Escherichia coli photoreactivating enzyme (PRE) has been purified in large amounts from an E.coli strain lysogenic for a defective lambda bacteriophage carrying the phr gene. The resulting enzyme had a pH optimum of 7.2 and an ionic strength optimum of 0.18. It consisted of an apoprotein and cofactor, both of which were necessary for catalytic activity. The apoprotein had a monomer molecular weight of 35,200 and showed stable aggregates under denaturing conditions. The amino acid analysis of the E.coli enzyme was very similar to that of the photoreactivating enzyme from orchid seedlings (Cattelya aurantiaca). Both had arginine at the amino terminus. The cofactor, like the holoenzyme, showed absorption, magnetic circular dichroism, and emission properties indicative of an adenine moiety. Although the isolated enzyme had an action spectrum which peaked at about 360 nm, neither the cofactor, apoenzyme nor holoenzyme showed any detectable absorption between 300 and 400 nm.

  1. Effects of prevalent freshwater chemical contaminants on in vitro growth of Escherichia coli and Klebsiella pneumoniae

    Energy Technology Data Exchange (ETDEWEB)

    Higgins, James [USDA-ARS, Bldg 173, 10300 Baltimore Ave., Beltsville, MD 20705 (United States)], E-mail: tarbandu12@juno.com; Hohn, Christina [NCSU College of Veterinary Medicine, Raleigh, NC 27606 (United States)

    2008-03-15

    Many surface and ground waters in the continental US are contaminated with a variety of chemical pollutants, which are usually present in concentrations in the ppm and ppb range. The effects of these pollutants on coliform bacteria, which are prominent members of the aquatic flora, are poorly understood. Using a microtiter plate assay, isolates of Escherichia coli (from chicken intestine and fresh water), and an isolate of Klebsiella pneumoniae (from bovine milk) were exposed to varying concentrations of common pollutants over a 24 h period. The herbicides/pesticides simazine, atrazine, and diazinon; the VOCs trichloroethene and MTBE; the estrogens estradiol and estrone; and caffeine, all failed to inhibit bacterial growth at ppm levels. Only ethylene glycol, and the herbicide 2,4-D, significantly inhibited bacterial growth compared to controls. These results suggest that the replication of coliform bacteria in fresh waters is not adversely impacted by many common pollutants. - Using a microtiter plate assay, E. coli and Klebsiella bacteria were exposed to a panel of common chemical pollutants of fresh water; only ethylene glycol and 2,4-D inhibited bacterial replication.

  2. Viability of Bifidobacterium bifidum and Escherichia coli in Versus Prebiotic Effects of Jerusalem Artichoke (Helianthus tuberosus

    Directory of Open Access Journals (Sweden)

    Elaheh Mansouri

    2016-10-01

    Full Text Available Background In this study, in vitro prebiotic effects of Jerusalem artichoke poly-fructans on the survivability and activity of Bifidobacterium bifidum, Escherichia coli were investigated and compared with HP-Inulin (a high molecular-weight fraction of chicory-derived inulin. Objectives The prebiotic potential of poly-fructans extracted from native Jerusalem artichoke tubers on the survivability of B. bifidum and E. coli was evaluated in this study. Methods In this experimental study, 24 treatments divided to 2 groups (Extracted poly-fructose from Jerusalem artichoke tubers and standard inulin randomly. The turbidity and pH variations during 48 hours incubation were determined using final concentrations of each group (0.5%, 1%, 2% and 3% (w/v. The data were analyzed by MINITAB 14 and MSTATC statistical software, one way ANOVA and Duncan’s test. Results This study suggests that Jerusalem artichoke tuber fructooligosaccharides (JA-Fr had the potential to be used as a prebiotic component. The growth of B. bifidum improved significantly in the presence of Jerusalem artichoke fructans compared to the control. There was no significant differences (P < 0.05 in Bifidobacterium population in different concentrations of Jerusalem artichoke poly-fructans, but the population was significantly higher than the count in the presence of HP-inulin. The pH decreased in both media during 48 hours incubation time. Specific rate of growth and doubling time determined for E. coli demonstrated that the efficacy of various carbon sources in stimulating bacterial growth were influenced by the concentration and DP (degree of polymerization of fructan chains in the media. Conclusions Jerusalem artichoke fructooligosaccharides can provide the greater stability of probiotics and acid production, so it can be considered as a potential source of high-yielding oligosaccharide for commercial prebiotic production to develop food industry and improve host health.

  3. Green tea as an effective antimicrobial for urinary tract infections caused by Escherichia coli

    Directory of Open Access Journals (Sweden)

    Wanda eReygaert

    2013-06-01

    Full Text Available Background: Urinary tract infections (UTIs are a very most common type of infection worldwide, and result in billions of dollars in medical care costs. Escherichia coli is the infective agent for 80%-90% of all UTIs. Green tea, derived from leaves of the Camellia sinensis plant has been shown to have various potential health benefits (e.g. cardiovascular disease and cancer. The major beneficial components of green tea have been characterized, and are now known to be polyphenolic catechins. The main catechins in green tea are (--epicatechin-3-gallate (ECG, (--epigallocatechin (EGC, (--epicatechin (EC, and (--epigallocatechin-3-gallate (EGCG. EGCG and EGC have been shown to have antimicrobial effects, but only EGC has been shown to be excreted in urine. Isolates of E. coli from urinary tract infections collected between 2007-2008 were characterized for antimicrobial resistance to standard drugs. Then 80 of these isolates, representing a wide spectrum of antimicrobial susceptibility patterns, were selected for testing using an extract of green tea.Results: The concentrations of green tea extract tested were 0, 2.5, 3.0, 3.5, and 4.0 mg/ml. All of the strains tested, except one, had MICs of ≤4.0 mg/ml, with 40% of the isolates having an MIC of ≤2.5 mg/ml, 36% of the isolates having an MIC of ≤3.0 mg/ml, 18% of the isolates having an MIC of ≤3.5 mg/ml, and 5% of the isolates having an MIC of ≤4.0 mg/ml. Two control strains varied in susceptibility, one having an MIC of ≤2.5 mg/ml, another having an MIC of ≤3.5 mg/ml, and the third having an MIC of ≤4.0 mg/ml.Conclusion: Since EGC has been shown to have antimicrobial effects on E. coli, and EGC has been shown to be excreted in the urine in a high enough concentration to potentially be effective as an antimicrobial; these MIC results suggest that ingesting green tea could have potential antimicrobial effects on urinary tract infections caused by E. coli.

  4. The in vitro synergistic inhibitory effect of human amniotic fluid and gentamicin on growth of Escherichia coli.

    Science.gov (United States)

    Miglioli, P A; Schoffel, U; Gianfranceschi, L

    1996-01-01

    The activity of serum and its synergistic effect with many antibiotics against bacteria are well known. Few reports are available on similar phenomena produced by human amniotic fluid (HAF). Thus we investigated the antibacterial activity of HAF and the presence of a synergistic effect with gentamicin (GM) against Escherichia coli strains. Antimicrobial activity was evaluated as a delay of the growth curve, using a turbidimetric method. E. coli ATCC 10798 and E. coli SC 12155 were employed as test micro-organisms in nutrient broth, and GM was used at a subinhibitory concentration. HAF exerted antibacterial activity and, cooperating with GM at subinhibitory concentration, enhanced its antibiotic activity against E. coli. The presence of Schlievert's glycoprotein in HAF could explain these results.

  5. Investigation of antibacterial effects of ethanolic extract of Sumac (Rhus coriaria L. against Escherichia coli in vitro

    Directory of Open Access Journals (Sweden)

    H Moshtaghi

    2013-08-01

    Full Text Available The antibacterial effect of etbhanolic extract of Sumac (Rhus coriaria L. was investigated quantitatively and qualitatively on Escherichia coli. The results of well diffusion test showed that extracts of Sumac in concentration of 0.5%, 1%, 2.5% and 5% could inhibited E. coli. In this study it was shown that MIC of the alcoholic extract of Sumac against E. coli was 6.25 mg/ml and its MBC against this bacterium was 50 mg/ml. The results from evaluation of the antibacterial effects of the Sumac revealed that at 4 and 15 °C, the growth of E. coli in test tubes containing meat extracts has increased Throughout the 48 h of incubation period. Results showed that the growth of this bacteria in different concentration of Sumac extract as decreased in the both tested temperatures in comparison to time zero (p

  6. FTIR nanobiosensors for Escherichia coli detection

    Directory of Open Access Journals (Sweden)

    Stefania Mura

    2012-07-01

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

  7. Inhibition of electron transfer and uncoupling effects by emodin and emodinanthrone in Escherichia coli.

    OpenAIRE

    Ubbink-Kok, T; Anderson, J A; Konings, W N

    1986-01-01

    The anthraquinones emodin (1,3,delta-trihydroxy-6-methylanthraquinone) and emodinanthrone (1,3,8-trihydroxy-6-methylanthrone) inhibited respiration-driven solute transport at micromolar concentrations in membrane vesicles of Escherichia coli. This inhibition was enhanced by Ca ions. The inhibitory action on solute transport is caused by inhibition of electron flow in the respiratory chain, most likely at the level between ubiquinone and cytochrome b, and by dissipation of the proton motive fo...

  8. Lethal and mutagenic effects of XeCl laser radiation on Escherichia coli bacteria

    International Nuclear Information System (INIS)

    Tiflova, O.A.; Karu, T.J.; Furzikov, N.P.; Karbysheva, E.A.

    1987-01-01

    The survival rate and reversion to tryptophan-independence of Escherichia coli after XeCl laser irradiation (λ=308 nm) within the dose range deom 10 3 to 10 5 J/m 2 have been studied to show that LD 37 is 10 4 J/m 2 , the survival rate at a maximum dose of 10 5 J/m 2 is 1 per cent, and the number of mutants per 10 6 cells survived is 100

  9. Enteroaggregative Escherichia coli in Daycare

    DEFF Research Database (Denmark)

    Hebbelstrup Jensen, Betina; Stensvold, Christen R.; Struve, Carsten

    2016-01-01

    Enteroaggregative Escherichia coli (EAEC) has been associated with persistent diarrhea, reduced growth acceleration, and failure to thrive in children living in developing countries and with childhood diarrhea in general in industrialized countries. The clinical implications of an EAEC carrier...... and answered a questionnaire regarding gastrointestinal symptoms and exposures. Exposures included foreign travel, consumption of antibiotics, and contact with a diseased animal. In the capital area of Denmark, a total of 179 children aged 0-6 years were followed in a cohort study, in the period between 2009...

  10. Effect of Light-Activated Hypocrellin B on the Growth and Membrane Permeability of Gram-Negative Escherichia coli Cells

    Directory of Open Access Journals (Sweden)

    Yuan Jiang

    2014-01-01

    Full Text Available Aim. To investigate the effect of light-activated hypocrellin B on the growth and membrane permeability of Gram-negative bacteria. Methods. Escherichia coli (E. coli as a model bacterium of Gram-negative bacteria was incubated with various concentrations of hypocrellin B for 60 min and was subsequently irradiated by blue light with wavelength of 470 nm at the dose of 12 J/cm2. Colony forming units were counted and the growth inhibition rate of E. coli cells was calculated after light-activated hypocrellin B. Membrane permeability was measured using flow cytometry and confocal laser scanning microscopy (CLSM with propidium iodide (PI staining. Bacterial morphology was observed using transmission electron microscopy (TEM. Reactive oxygen species in bacterial cells were measured using flow cytometry with DCFH-DA staining. Results. Significant growth inhibition rate of E. coli cells was observed after photodynamic action of hypocrellin B. Remarkable damage to the ultrastructure of E. coli was also observed by TEM. Flow cytometry and CLSM observation showed that light-activated hypocrellin B markedly increased membrane permeability of E. coli. Flow cytometry showed the intracellular ROS increase in E. coli treated by photodynamic action of hypocrellin B. Conclusion. Light-activated hypocrellin B caused intracellular ROS increase and structural damages and inhibited the growth of Gram-negative E. coli cells.

  11. WGS accurately predicts antimicrobial resistance in Escherichia coli

    Science.gov (United States)

    Objectives: To determine the effectiveness of whole-genome sequencing (WGS) in identifying resistance genotypes of multidrug-resistant Escherichia coli (E. coli) and whether these correlate with observed phenotypes. Methods: Seventy-six E. coli strains were isolated from farm cattle and measured f...

  12. Studies of biological effects of fluoride stannous and UV short in Escherichia coli BH110

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira da C, R., E-mail: rogercosta1@hotmail.com [Federal Institute of Education, Science and Technology of Goias, Campus Uruacu, Rua Formosa Qd 28 e 29, Loteamento Santana, 76400-000 Uruacu, Goias (Brazil)

    2015-10-15

    Full text: The amount of UV rays on the Earth's surface has increased due to depletion of the ozone layer, and this has worried society, since these radiation although not considered ionizing can cause damage to biological membrane and especially to DNA. The DNA has cell repair mechanisms that can work in lesions caused by electromagnetic radiation such as ultraviolet -short (UV C)and agents causing oxidative stress, such as tin salts. Among the repair mechanisms can highlight the adaptive repair, which consists of smaller doses to cells pre-exposure of an oxidizing agent, and when these cells are exposed to larger doses of the agent even if there is a reduction in mortality rate which leads to complete that repair mechanisms are activated in the pre-exposure reducing cell mortality. Several publications have shown the genotoxic effects of stannous salts such as stannous fluoride (SnF{sub 2}), which shows the importance of the study, since these salts are widely used in industry as components in toothpastes and mouthwashes. So we check whether pretreatment with UV C is able to induce adaptive response reducing the cytotoxic effects caused by exposure of the strains to SnF{sub 2}. We use a strain of Escherichia coli BH110 (BH110 E. coli) deficient in three genes (fpg, nfo and xth) involved in the excision repair bases. To verify the induction of adaptive response to strain BH110 was exposed to various doses of UV C and then treated with SnF{sub 2} a concentration of 110 u M. Our results showed that the LD10 of strain BH110 is 20 J/m{sup 2} and pre-treatment with UV C does not seem to induce adaptive repair in BH110 strains. (Author)

  13. Modified Vero cell induced by Bifidobacterium bifidum inhibits enterohemorrhagic Escherichia coli O157:H7 cytopathic effect

    Directory of Open Access Journals (Sweden)

    Tahamtan, Y.

    2014-11-01

    Full Text Available Enterohemorrhagic Escherichia coli (EHEC, such as E. coli O157:H7, are emerging food-borne pathogens worldwide. This micro-organism can damage the epithelial tissue of the large intestine. The cytotoxic effects can be neutralized by probiotics such as Bifidobacterium bifidum. Probiotics are viable cells that have beneficial effects on the health of the host. The preventing activity of B. bifidum against E. coli O157 was studied using a Vero cell model. Vero cell was pretreated with viable B. bifidum and incubated for either 3 h to 24 h and then collected from the cell to make modified Vero cell (MVC. Indirect antibacterial effects of B. bifidum were demonstrated by reduction of attachment of E. coli O157:H7 to MVC. The maximum reduction was resulted in pretreatment of Vero cell with B. bifidum for 24 h before infection. B. bifidum attenuated E. coli O157:H7 attachment to MVC up to 10 days of incubation. To our knowledge, MCV prevented Vero cell line injury induced by E. coli O157:H7. Therefore, B. bifidum can be used for inhibition of E. coli O157:H7 cytopathic effect (CPE in Vero cell model, even as pretreatment of the cell line.

  14. Radiochemical method for evaluating the effect of antibiotics on Escherichia coli biofilms

    International Nuclear Information System (INIS)

    Dix, B.A.; Cohen, P.S.; Laux, D.C.; Cleeland, R.

    1988-01-01

    A simple radiochemical method for evaluating the action of antibiotics on Escherichia coli cells in biofilms is reported. After growth, biofilms of E. coli ATCC 25922 on disks of urinary catheter material were suspended in fresh medium containing or lacking an antibiotic, incubated for 4 h at 37 degrees C, and pulse-labeled with [ 3 H]leucine for 5 min. Radioactivity in trichloracetic acid-precipitable material in the biofilm and in the surrounding medium (planktonic E. coli) was then measured. Antibiotic-induced inhibition of incorporation of [ 3 H]leucine into the cells in the biofilm was far less pronounced than incorporation into planktonic cells and, furthermore, correlated well with loss in viable counts. The method is simple, inexpensive, and extremely timesaving

  15. Effects of disruption of heat shock genes on susceptibility of Escherichia coli to fluoroquinolones

    Directory of Open Access Journals (Sweden)

    Morioka Mizue

    2003-08-01

    Full Text Available Abstract Background It is well known that expression of certain bacterial genes responds rapidly to such stimuli as exposure to toxic chemicals and physical agents. It is generally believed that the proteins encoded in these genes are important for successful survival of the organism under the hostile conditions. Analogously, the proteins induced in bacterial cells exposed to antibiotics are believed to affect the organisms' susceptibility to these agents. Results We demonstrated that Escherichia coli cells exposed to levofloxacin (LVFX, a fluoroquinolone (FQ, induce the syntheses of heat shock proteins and RecA. To examine whether the heat shock proteins affect the bactericidal action of FQs, we constructed E. coli strains with mutations in various heat shock genes and tested their susceptibility to FQs. Mutations in dnaK, groEL, and lon increased this susceptibility; the lon mutant exhibited the greatest effects. The increased susceptibility of the lon mutant was corroborated by experiments in which the gene encoding the cell division inhibitor, SulA, was subsequently disrupted. SulA is induced by the SOS response and degraded by the Lon protease. The findings suggest that the hypersusceptibility of the lon mutant to FQs could be due to abnormally high levels of SulA protein resulting from the depletion of Lon and the continuous induction of the SOS response in the presence of FQs. Conclusion The present results show that the bactericidal action of FQs is moderately affected by the DnaK and GroEL chaperones and strongly affected by the Lon protease. FQs have contributed successfully to the treatment of various bacterial infections, but their widespread use and often misuse, coupled with emerging resistance, have gradually compromised their utility. Our results suggest that agents capable of inhibiting the Lon protease have potential for combination therapy with FQs.

  16. PATHOGENIC POTENTIALS OF ESCHERICHIA COLI ISOLATED ...

    African Journals Online (AJOL)

    Electrolyte and haematological parameters in rabbits infected with pathogenic isolates of Escherichia coli from rural water supplies in Rivers State, Nigeria, where monitored. Rabbits were orally infected with suspension containing 3x107 cfu /ml of Escherichia coli to induce diarrhoea, and the electrolyte (sodium, potassium ...

  17. Atomic force microscopy study of the antibacterial effects of chitosans on Escherichia coli and Staphylococcus aureus

    Energy Technology Data Exchange (ETDEWEB)

    Eaton, Peter [REQUIMTE, Departamento de Quimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal)], E-mail: peter.eaton@fc.up.pt; Fernandes, Joao C. [Departamento de Quimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Pereira, Eulalia [REQUIMTE, Departamento de Quimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Pintado, Manuela E.; Xavier Malcata, F. [Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)

    2008-09-15

    Chitosan has been reported to be a non-toxic, biodegradable antibacterial agent. The aim of this work was to elucidate the relationship between the molecular weight of chitosan and its antimicrobial activity upon two model microorganisms, one Gram-positive (Staphylococcus aureus) and one Gram-negative (Escherichia coli). Atomic force microscopy (AFM) imaging was used to obtain high-resolution images of the effect of chitosans on the bacterial morphology. The AFM measurements were correlated with viable cell numbers, which show that the two species reacted differently to the high- and low-molecular-weight chitosan derivatives. The images obtained revealed not only the antibacterial effects, but also the response strategies used by the bacteria; cell wall collapse and morphological changes reflected cell death, whereas clustering of bacteria appeared to be associated with cell survival. In addition, nanoindentation experiments with the AFM revealed mechanical changes in the bacterial cell wall induced by the treatment. The nanoindentation results suggested that despite little modification observed in the Gram-positive bacteria in morphological studies, cell wall damage had indeed occurred, since cell wall stiffness was reduced after chitooligosaccharide treatment.

  18. Atomic force microscopy study of the antibacterial effects of chitosans on Escherichia coli and Staphylococcus aureus

    International Nuclear Information System (INIS)

    Eaton, Peter; Fernandes, Joao C.; Pereira, Eulalia; Pintado, Manuela E.; Xavier Malcata, F.

    2008-01-01

    Chitosan has been reported to be a non-toxic, biodegradable antibacterial agent. The aim of this work was to elucidate the relationship between the molecular weight of chitosan and its antimicrobial activity upon two model microorganisms, one Gram-positive (Staphylococcus aureus) and one Gram-negative (Escherichia coli). Atomic force microscopy (AFM) imaging was used to obtain high-resolution images of the effect of chitosans on the bacterial morphology. The AFM measurements were correlated with viable cell numbers, which show that the two species reacted differently to the high- and low-molecular-weight chitosan derivatives. The images obtained revealed not only the antibacterial effects, but also the response strategies used by the bacteria; cell wall collapse and morphological changes reflected cell death, whereas clustering of bacteria appeared to be associated with cell survival. In addition, nanoindentation experiments with the AFM revealed mechanical changes in the bacterial cell wall induced by the treatment. The nanoindentation results suggested that despite little modification observed in the Gram-positive bacteria in morphological studies, cell wall damage had indeed occurred, since cell wall stiffness was reduced after chitooligosaccharide treatment

  19. Effectiveness of sanitizing agents in inactivating Escherichia coli (ATCC 25922 in food cutting board surfaces. Removal E. coli using different sanitizers

    Directory of Open Access Journals (Sweden)

    CEZAR AUGUSTO BELTRAME

    2016-03-01

    Full Text Available The objective of this study was to investigate Escherichia coli adhesion on new and used polyethylene cutting board surface and evaluate it’s removal using different sanitizer (peracetic acid,chlorhexidine, sodium hypochlorite and organic acids. Results indicated that the number of adherent cells increased with time in both surfaces evaluated. Evaluating the sanitizer action, 0.5%peracetic acid was more effective in removal E. coli than chlorhexidine and organic acids at same concentration in both surfaces. Peracetic acid and sodium hypochlorite also showed effectiveness at concentrations of 0.2% and 0.5% on new surfaces, respectively. 0.8% of chlorhexidine and 2.0% of organic acids showed similar effectiveness in the removal E. coli on new and used surfaces, respectively.These results suggest that peracetic acid is considerable promise sanitizer for application in surfaces of the food processing industry.

  20. Phenotypic plasticity and effects of selection on cell division symmetry in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Uttara N Lele

    Full Text Available Aging has been demonstrated in unicellular organisms and is presumably due to asymmetric distribution of damaged proteins and other components during cell division. Whether the asymmetry-induced aging is inevitable or an adaptive and adaptable response is debated. Although asymmetric division leads to aging and death of some cells, it increases the effective growth rate of the population as shown by theoretical and empirical studies. Mathematical models predict on the other hand, that if the cells divide symmetrically, cellular aging may be delayed or absent, growth rate will be reduced but growth yield will increase at optimum repair rates. Therefore in nutritionally dilute (oligotrophic environments, where growth yield may be more critical for survival, symmetric division may get selected. These predictions have not been empirically tested so far. We report here that Escherichia coli grown in oligotrophic environments had greater morphological and functional symmetry in cell division. Both phenotypic plasticity and genetic selection appeared to shape cell division time asymmetry but plasticity was lost on prolonged selection. Lineages selected on high nutrient concentration showed greater frequency of presumably old or dead cells. Further, there was a negative correlation between cell division time asymmetry and growth yield but there was no significant correlation between asymmetry and growth rate. The results suggest that cellular aging driven by asymmetric division may not be hardwired but shows substantial plasticity as well as evolvability in response to the nutritional environment.

  1. Effects of electron acceptors on removal of antibiotic resistant Escherichia coli, resistance genes and class 1 integrons under anaerobic conditions.

    Science.gov (United States)

    Yuan, Heyang; Miller, Jennifer H; Abu-Reesh, Ibrahim M; Pruden, Amy; He, Zhen

    2016-11-01

    Anaerobic biotechnologies can effectively remove antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), but there is a need to better understand the mechanisms. Here we employ bioelectrochemical systems (BES) as a platform to investigate the fate of a native tetracycline and sulfonamide-resistant Escherichia coli strain and its ARGs. The E. coli strain carrying intI1, sulI and tet(E) was isolated from domestic wastewater and dosed into a tubular BES. The BES was first operated as a microbial fuel cell (MFC), with aeration in the cathode, which resulted in enhanced removal of E. coli and ARGs by ~2 log (i.e., order of magnitude) when switched from high current to open circuit operation mode. The BES was then operated as a microbial electrolysis cell (MEC) to exclude the effects of oxygen diffusion, and the removal of E. coli and ARGs during the open circuit configuration was again 1-2 log higher than that at high current mode. Significant correlations of E. coli vs. current (R(2)=0.73) and ARGs vs. E. coli (R(2) ranged from 0.54 to 0.87), and the fact that the BES substrate contained no electron acceptors, implied that the persistence of the E. coli and its ARGs was determined by the availability of indigenous electron acceptors in the BES, i.e., the anode electrode or the electron shuttles generated by the exoelectrogens. Subsequent experiments with pure-culture tetracycline and sulfonamide-resistant E. coli being incubated in a two-chamber MEC and serum bottles demonstrated that the E. coli could survive by respiring anode electrode and/or electron shuttles released by exoelectrogens, and ARGs persisted with their host E. coli. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Graphene Field-Effect Transistors for the Sensitive and Selective Detection of Escherichia coli Using Pyrene-Tagged DNA Aptamer.

    Science.gov (United States)

    Wu, Guangfu; Dai, Ziwen; Tang, Xin; Lin, Zihong; Lo, Pik Kwan; Meyyappan, M; Lai, King Wai Chiu

    2017-10-01

    This study reports biosensing using graphene field-effect transistors with the aid of pyrene-tagged DNA aptamers, which exhibit excellent selectivity, affinity, and stability for Escherichia coli (E. coli) detection. The aptamer is employed as the sensing probe due to its advantages such as high stability and high affinity toward small molecules and even whole cells. The change of the carrier density in the probe-modified graphene due to the attachment of E. coli is discussed theoretically for the first time and also verified experimentally. The conformational change of the aptamer due to the binding of E. coli brings the negatively charged E. coli close to the graphene surface, increasing the hole carrier density efficiently in graphene and achieving electrical detection. The binding of negatively charged E. coli induces holes in graphene, which are pumped into the graphene channel from the contact electrodes. The carrier mobility, which correlates the gate voltage to the electrical signal of the APG-FETs, is analyzed and optimized here. The excellent sensing performance such as low detection limit, high sensitivity, outstanding selectivity and stability of the graphene biosensor for E. coli detection paves the way to develop graphene biosensors for bacterial detection. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Enhanced sensitivity to the lethal and mutagenic effects of photosensitizing action of chlorpromazine in ethylenediaminetetraacetate-treated Escherichia coli

    International Nuclear Information System (INIS)

    Yonei, S.; Todo, T.

    1982-01-01

    Ethylenediaminetetraacetate (EDTA) treatment of Escherichia coli H/r30 (Arg - ) enhanced cell sensitivity to the lethal and mutagenic effects of the photosensitizing action of chlorpromazine (CPZ). The most obvious effect of EDTA on the fluence-survival curve was an elimination of the shoulder. In the absence of EDTA, CPZ plus near-UV radiation did not induce the reversion from arginine-auxotroph to autotroph of E. coli H/r30. However, when EDTA (5 mM)-treated cells were subjected to CPZ plus near-UV radiation, the induced reversion frequency increased with time of irradiation. It is concluded that the enhanced penetration of CPZ into E. coli cells by EDTA facilitates the drug binding to DNA within the cells upon near-UV irradiation and that this is the cause for the enhanced photosensitized lethal and mutagenic effects of CPZ. (author)

  4. Prodigiosin - A Multifaceted Escherichia coli Antimicrobial Agent.

    Directory of Open Access Journals (Sweden)

    Tjaša Danevčič

    Full Text Available Despite a considerable interest in prodigiosin, the mechanism of its antibacterial activity is still poorly understood. In this work, Escherichia coli cells were treated with prodigiosin to determine its antimicrobial effect on bacterial physiology. The effect of prodigiosin was concentration dependent. In prodigiosin treated cells above MIC value no significant DNA damage or cytoplasmic membrane disintegration was observed. The outer membrane, however, becomes leaky. Cells had severely decreased respiration activity. In prodigiosin treated cells protein and RNA synthesis were inhibited, cells were elongated but could not divide. Pre-treatment with prodigiosin improved E. coli survival rate in media containing ampicillin, kanamycin and erythromycin but not phleomycin. The results suggest that prodigiosin acts as a bacteriostatic agent in E. coli cells. If prodigiosin was diluted, cells resumed growth. The results indicate that prodigiosin has distinct mode of antibacterial action in different bacteria.

  5. The effects of combined treatment of irradiation and heat on bacteria escherichia coli and sarcina lutea in dry condition

    International Nuclear Information System (INIS)

    Nikham; Hilmy, Nazly

    1987-01-01

    The effects of combination treatment of irradiation and heat on bacteria escherichia coli and sarcina lutea in dry condition. Investigation on the effects of combined irradiation + heat and heat + irradiation treatments have been carried out i.e. at the doses of 0; 1.0; 1.5; and 2.0 kGy with heating at 50 0 C for 10; 20; and 30 minutes on escherichia coli B/r, escherichia coli from sludge and sarcine lutea. Samples of bacteria were prepared in dry condition by using sterile fine sand as carrier. Irradiation was done in aerobic condition with RH 90% and the time range between irradiation and heating was not more than 2 hours. The results showed that the D 10 value did not give significant difference between the combined irradiation + heat, and heat + irradiation treatments for the 3 species of bacteria, compared to irradiation only (p 0.05). Doses of 1.0 and 1.5 kGy combined with heating at 50 0 C for 10 and 20 minutes gave better results compared to irradiation only. 17 refs

  6. Localization of protein aggregation in Escherichia coli is governed by diffusion and nucleoid macromolecular crowding effect.

    Directory of Open Access Journals (Sweden)

    Anne-Sophie Coquel

    2013-04-01

    Full Text Available Aggregates of misfolded proteins are a hallmark of many age-related diseases. Recently, they have been linked to aging of Escherichia coli (E. coli where protein aggregates accumulate at the old pole region of the aging bacterium. Because of the potential of E. coli as a model organism, elucidating aging and protein aggregation in this bacterium may pave the way to significant advances in our global understanding of aging. A first obstacle along this path is to decipher the mechanisms by which protein aggregates are targeted to specific intercellular locations. Here, using an integrated approach based on individual-based modeling, time-lapse fluorescence microscopy and automated image analysis, we show that the movement of aging-related protein aggregates in E. coli is purely diffusive (Brownian. Using single-particle tracking of protein aggregates in live E. coli cells, we estimated the average size and diffusion constant of the aggregates. Our results provide evidence that the aggregates passively diffuse within the cell, with diffusion constants that depend on their size in agreement with the Stokes-Einstein law. However, the aggregate displacements along the cell long axis are confined to a region that roughly corresponds to the nucleoid-free space in the cell pole, thus confirming the importance of increased macromolecular crowding in the nucleoids. We thus used 3D individual-based modeling to show that these three ingredients (diffusion, aggregation and diffusion hindrance in the nucleoids are sufficient and necessary to reproduce the available experimental data on aggregate localization in the cells. Taken together, our results strongly support the hypothesis that the localization of aging-related protein aggregates in the poles of E. coli results from the coupling of passive diffusion-aggregation with spatially non-homogeneous macromolecular crowding. They further support the importance of "soft" intracellular structuring (based on

  7. Effects of combination of magnesium and zinc oxide nanoparticles and heat on Escherichia coli and Staphylococcus aureus bacteria in milk

    Directory of Open Access Journals (Sweden)

    M. Kimiaee Sadr

    2016-01-01

    Full Text Available Objective: The objective of this study was to investigate the antibacterial activities of combination of MgO and ZnO nanoparticles in the presence of heat against Escherichia coli and Staphylococcus aureus. Materials and Methods:Bacteria were grown on either agar or broth media followed by the addition of ZnO and MgO nanoparticles. Then the combined effect of ZnO and MgO nanoparticles was investigated.  Furthermore, the media containing nanoparticles were treated with mild heat and their synergistic antibacterial activity was investigated against E. coli and S. aureus in milk. Results: The data showed that the nanoparticles used in this study had no effect on the bacteria in the agar medium. However, the results showed that ZnO and MgO nanoparticles resulted in a significant decrease in the number of E. coli (P

  8. Effects of electron acceptors on removal of antibiotic resistant Escherichia coli, resistance genes and class 1 integrons under anaerobic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Heyang; Miller, Jennifer H. [Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); Abu-Reesh, Ibrahim M. [Department of Chemical Engineering, Qatar University, P.O. Box 2713, Doha (Qatar); Pruden, Amy [Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); He, Zhen, E-mail: zhenhe@vt.edu [Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States)

    2016-11-01

    Anaerobic biotechnologies can effectively remove antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), but there is a need to better understand the mechanisms. Here we employ bioelectrochemical systems (BES) as a platform to investigate the fate of a native tetracycline and sulfonamide-resistant Escherichia coli strain and its ARGs. The E. coli strain carrying intI1, sulI and tet(E) was isolated from domestic wastewater and dosed into a tubular BES. The BES was first operated as a microbial fuel cell (MFC), with aeration in the cathode, which resulted in enhanced removal of E. coli and ARGs by ~ 2 log (i.e., order of magnitude) when switched from high current to open circuit operation mode. The BES was then operated as a microbial electrolysis cell (MEC) to exclude the effects of oxygen diffusion, and the removal of E. coli and ARGs during the open circuit configuration was again 1–2 log higher than that at high current mode. Significant correlations of E. coli vs. current (R{sup 2} = 0.73) and ARGs vs. E. coli (R{sup 2} ranged from 0.54 to 0.87), and the fact that the BES substrate contained no electron acceptors, implied that the persistence of the E. coli and its ARGs was determined by the availability of indigenous electron acceptors in the BES, i.e., the anode electrode or the electron shuttles generated by the exoelectrogens. Subsequent experiments with pure-culture tetracycline and sulfonamide-resistant E. coli being incubated in a two-chamber MEC and serum bottles demonstrated that the E. coli could survive by respiring anode electrode and/or electron shuttles released by exoelectrogens, and ARGs persisted with their host E. coli. - Highlights: • The fate of an antibiotic resistant E. coli stain and its ARGs in BES is studied. • The removal of the E. coli and its ARGs is enhanced with decreased current. • The ARGs are removed when the host E. coli dies and persist when the host survives. • The survival of the E. coli depends

  9. Effects of electron acceptors on removal of antibiotic resistant Escherichia coli, resistance genes and class 1 integrons under anaerobic conditions

    International Nuclear Information System (INIS)

    Yuan, Heyang; Miller, Jennifer H.; Abu-Reesh, Ibrahim M.; Pruden, Amy; He, Zhen

    2016-01-01

    Anaerobic biotechnologies can effectively remove antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), but there is a need to better understand the mechanisms. Here we employ bioelectrochemical systems (BES) as a platform to investigate the fate of a native tetracycline and sulfonamide-resistant Escherichia coli strain and its ARGs. The E. coli strain carrying intI1, sulI and tet(E) was isolated from domestic wastewater and dosed into a tubular BES. The BES was first operated as a microbial fuel cell (MFC), with aeration in the cathode, which resulted in enhanced removal of E. coli and ARGs by ~ 2 log (i.e., order of magnitude) when switched from high current to open circuit operation mode. The BES was then operated as a microbial electrolysis cell (MEC) to exclude the effects of oxygen diffusion, and the removal of E. coli and ARGs during the open circuit configuration was again 1–2 log higher than that at high current mode. Significant correlations of E. coli vs. current (R"2 = 0.73) and ARGs vs. E. coli (R"2 ranged from 0.54 to 0.87), and the fact that the BES substrate contained no electron acceptors, implied that the persistence of the E. coli and its ARGs was determined by the availability of indigenous electron acceptors in the BES, i.e., the anode electrode or the electron shuttles generated by the exoelectrogens. Subsequent experiments with pure-culture tetracycline and sulfonamide-resistant E. coli being incubated in a two-chamber MEC and serum bottles demonstrated that the E. coli could survive by respiring anode electrode and/or electron shuttles released by exoelectrogens, and ARGs persisted with their host E. coli. - Highlights: • The fate of an antibiotic resistant E. coli stain and its ARGs in BES is studied. • The removal of the E. coli and its ARGs is enhanced with decreased current. • The ARGs are removed when the host E. coli dies and persist when the host survives. • The survival of the E. coli depends on the

  10. Action of sodium deoxycholate on Escherichia coli

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  11. Action of sodium deoxycholate on Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-08-01

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

  12. Effect of low-frequency electromagnetic fields on the Escherichia coli growth for application in riverbank filtration

    Science.gov (United States)

    Selamat, Rossitah; Abustan, Ismail; Arshad, Mohd Rizal; Kamal, Nurul Hana Mokhtar

    2017-10-01

    A 50 Hz low-frequency electromagnetic field (LF-EMF) could give removal effect on the growth of Escherichia coli (E. coli) in the riverbank filtration (RBF) was studied. The LF-EMF strengths were varied from 2 to 10 mT using coil column induce magnetic fields. For this study, two different columns with a diameter of 50 mm and 80 mm were applied; 1.5mm copper wires with the number of turns between 300 to 600 turns. Water samples were flowed into the column at flowrate of 50mL/min with temperature in range of 28-30°C. This study, it was found that the LF-EMF has significant removal effects on E. coli growth, where the removal of 100% of E. coli at 6 mT and 8 mT after 6 hrs exposed. Moreover, for shorter exposure period of 3 hrs exposed, 82% of E. coli removal were detected in 80 mm column for 8 mT and 10 mT magnetic field. These findings indicate that the application of LF-EMF is able to decrease the E. coli, can be and efficient in E. coli growth from river water intake. Thus, the results from this study proved that the utilization of LF-EMF is able to decrease the concentrations of E. coli, and contributes in slowing down their growth. Also, it can be indicated that the LF-EMF kill a part of E. coli exposed in the river water with the large magnetic field and long-time exposure.

  13. Effect of Oxygen Limitation and Starvation on the Benzalkonium Chloride Susceptibility of Escherichia coli

    DEFF Research Database (Denmark)

    Bjergbæk, L.A.; Haagensen, Janus Anders Juul; Molin, Søren

    2008-01-01

    the gfp-tagged E. coli K-12 strain MG1655[pOX38Km]. Increasing temperature from 10 degrees C to 30 degrees C increased the bactericidal effect of BAC for both starved and nonstarved E. coli under aerobic and anaerobic conditions. The lowest minimum bactericidal concentration was observed for cells...

  14. Effects of zinc supplementation on Shiga toxin 2e-producing Escherichia coli in vitro.

    Science.gov (United States)

    Uemura, Ryoko; Katsuge, Tomoko; Sasaki, Yosuke; Goto, Shinya; Sueyoshi, Masuo

    2017-10-07

    Swine edema disease is caused by Shiga toxin (Stx) 2e-producing Escherichia coli (STEC). Addition of highly concentrated zinc formulations to feed has been used to treat and prevent the disease, but the mechanism of the beneficial effect is unknown. The purpose of the present study was to investigate the effects of highly concentrated zinc formulations on bacterial growth, hemolysin production, and an Stx2e release by STEC in vitro. STEC strain MVH269 isolated from a piglet with edema disease was cultured with zinc oxide (ZnO) or with zinc carbonate (ZnCO 3 ), each at up to 3,000 ppm. There was no effect of zinc addition on bacterial growth. Nonetheless, the cytotoxic activity of Stx2e released into the supernatant was significantly attenuated in the zinc-supplemented media compared to that in the control, with the 50% cytotoxic dose values of 163.2 ± 12.7, 211.6 ± 33.1 and 659.9 ± 84.2 after 24 hr of growth in the presence of ZnO, ZnCO 3 , or no supplemental zinc, respectively. The hemolytic zones around colonies grown on sheep blood agar supplemented with zinc were significantly smaller than those of colonies grown on control agar. Similarly, hemoglobin absorbance after exposure to the supernatants of STEC cultures incubated in sheep blood broth supplemented with zinc was significantly lower than that resulting from exposure to the control supernatant. These in vitro findings indicated that zinc formulations directly impair the factors associated with the virulence of STEC, suggesting a mechanism by which zinc supplementation prevents swine edema disease.

  15. Effect of a lytic bacteriophage on rabbits experimentally infected with pathogenic Escherichia coli

    Directory of Open Access Journals (Sweden)

    J. Zhao

    2017-09-01

    Full Text Available Pathogenic Escherichia coli (E. coli is severely threatening the rabbit industry in China, and the concern over antibiotic-resistant bacteria has given rise to an urgent need for antibiotic alternatives. In this study, a member (ZRP1 of the Myoviridae family was isolated from rabbit faeces using a strain of rabbit atypical enteropathogenic E. coli (ZR1 as host. The one-step growth curve indicated that the latent period was around 25 to 30 min and the burst size was 144±31 plaque-forming unit/cell. The rate of phage-resistant mutation was 7×10–5±4×10–5. When the bacteriophage input at the multiplicity of infection (MOI was 0.1, 1 or 10, the growth of host E. coli in broth was inhibited for 5 h. A single intravenous injection of ZRP1 at MOI 0.1, 1 or 10 significantly prolonged the survival time of rabbits which simultaneously received a lethal dose of ZR1.

  16. In vitro anti-bacterial and anti-adherence effects of Lactobacillus delbrueckii subsp bulgaricus on Escherichia coli.

    Science.gov (United States)

    Abedi, D; Feizizadeh, S; Akbari, V; Jafarian-Dehkordi, A

    2013-10-01

    Considering the emergence of antibiotic resistance, scientists are interested in using new antimicrobial agents in the treatment of infectious diseases including infections of the enteric systems. Lactic acid bacteria have the great potential to produce antimicrobial compounds that inhibit and control pathogenic bacteria. The aim of this study was to determine the anti-bacterial and anti-adherence properties of Lactobacillus delbrueckii subsp bulgaricus against Escherichia coli. The antibacterial activity of L. delbrueckii was investigated using disc diffusion and spot on lawn methods. In vitro anti-adhesion effect of L. delbrueckii against E. coli was examined using Caco-2 cells. In anti-adhesion assay, three competition conditions including competitive inhibition, adhesion inhibition, and displacement were examined. In spot on lawn method the zone of growth inhibition of E. coli by L. delbrueckii was 21.1 mm. The cell free supernatant of L. delbrueckii showed a good antibacterial activity against E. coli which was mainly related to lactic acid produced by L. delbrueckii. When two bacteria added simultaneously (competitive inhibition) degree of inhibition of E. coli binding by L. delbrueckii was 77%. In adhesion inhibition assay, L. delbrueckii was able to exclude E. coli adherence by around 43.5%. Displacement assay showed that L. delbrueckii had strong displacement ability toward E. coli and reduction of E. coli attachment by bound L. delbrueckii was 81.3%. The results suggest that L. delbrueckii may be able to inhibit E. coli infection in the gut; however more studies including in vivo studies need to be performed.

  17. Effect of Spermidine Analogues on Cell Growth of Escherichia coli Polyamine Requiring Mutant MA261.

    Directory of Open Access Journals (Sweden)

    Taketo Yoshida

    Full Text Available The effects of spermidine analogues [norspermidine (NSPD, 33, spermidine (SPD, 34, homospermidine (HSPD, 44 and aminopropylcadaverine (APCAD, 35] on cell growth were studied using Escherichia coli polyamine-requiring mutant MA261. Cell growth was compared at 32°C, 37°C, and 42°C. All four analogues were taken up mainly by the PotABCD spermidine-preferential uptake system. The degree of stimulation of cell growth at 32°C and 37°C was NSPD ≥ SPD ≥ HSPD > APCAD, and SPD ≥ HSPD ≥ NSPD > APCAD, respectively. However, at 42°C, it was HSPD » SPD > NSPD > APCAD. One reason for this is HSPD was taken up effectively compared with other triamines. In addition, since natural polyamines (triamines and teteraamines interact mainly with RNA, and the structure of RNA is more flexible at higher temperatures, HSPD probably stabilized RNA more tightly at 42°C. We have thus far found that 20 kinds of protein syntheses are stimulated by polyamines at the translational level. Among them, synthesis of OppA, RpoE and StpA was more strongly stimulated by HSPD at 42°C than at 37°C. Stabilization of the initiation region of oppA and rpoE mRNA was tighter by HSPD at 42°C than 37°C determined by circular dichroism (CD. The degree of polyamine stimulation of OppA, RpoE and StpA synthesis by NSPD, SPD and APCAD was smaller than that by HSPD at 42°C. Thus, the degree of stimulation of cell growth by spermidine analogues at the different temperatures is dependent on the stimulation of protein synthesis by some components of the polyamine modulon.

  18. Synergistic effect of enterocin AS-48 in combination with outer membrane permeabilizing treatments against Escherichia coli O157:H7.

    Science.gov (United States)

    Ananou, S; Gálvez, A; Martínez-Bueno, M; Maqueda, M; Valdivia, E

    2005-01-01

    To determine the effects of outer membrane (OM) permeabilizing agents on the antimicrobial activity of enterocin AS-48 against Escherichia coli O157:H7 CECT 4783 strain in buffer and apple juice. We determined the influence of pH, EDTA, sodium tripolyphosphate (STPP) and heat on E. coli O157:H7 CECT 4783 sensitivity to enterocin AS-48 in buffer and in apple juice. Enterocin AS-48 was not active against intact cells of E. coli O157:H7 CECT 4783 at neutral pH. However, cells sublethally injured by OM permeabilizing agents (EDTA, STPP, pH 5, pH 8.6 and heat) became sensitive to AS-48, decreasing the amount of bacteriocin required for inhibition of E. coli O157:H7 CECT 4783. The results presented indicate that enterocin AS-48 could potentially be applied with a considerably wider range of protective agents, such as OM permeabilizing agents, with increased efficacy in inhibiting E. coli O157:H7. Results from this study support the potential use of enterocin AS-48 to control E. coli O157:H7 in combination with other hurdles.

  19. Sequential effect of phages and cold nitrogen plasma against Escherichia coli O157:H7 biofilms on different vegetables.

    Science.gov (United States)

    Cui, Haiying; Bai, Mei; Yuan, Lu; Surendhiran, Duraiarasan; Lin, Lin

    2018-03-02

    Escherichia coli O157:H7 (E. coli O157:H7) is one of the most common pathogens in fresh vegetables and fruits, and most of the diseases produced by E. coli O157:H7 are associated with biofilms. Cold nitrogen plasma (CNP) is a cold sterilization technique which has no residue. However to completely eliminate the biofilm on the surface of vegetables the processing power and time of CNP have to be enhanced, which will impact on the quality of fruits and vegetables. Thus the sequential treatment of CNP and phage techniques was engineered in this study. Compared to treatment performed separately, sequential treatment not only had more mild treatment conditions as 400W CNP treatment for 2min and 5% phage treatment for 30min, but also exhibited more remarkable effect on eradicating E. coli O157:H7 biofilms in vitro and on vegetables. The population of E. coli O157:H7 was approximately reduced by 2logCFU/cm 2 after individual treatment of 5% phages for 30min or 500W CNP for 3min. While the sequential treatment of CNP (400W, 2min) and phages (5%, 30min) reduced the E. coli O157:H7 viable count in biofilm by 5.71logCFU/cm 2 . Therefore, the sequential treatment holds a great promise to improve the current treatment systems of bacterial contamination on different vegetable surfaces. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Peptidoglycan Hydrolases of Escherichia coli

    Science.gov (United States)

    van Heijenoort, Jean

    2011-01-01

    Summary: The review summarizes the abundant information on the 35 identified peptidoglycan (PG) hydrolases of Escherichia coli classified into 12 distinct families, including mainly glycosidases, peptidases, and amidases. An attempt is also made to critically assess their functions in PG maturation, turnover, elongation, septation, and recycling as well as in cell autolysis. There is at least one hydrolytic activity for each bond linking PG components, and most hydrolase genes were identified. Few hydrolases appear to be individually essential. The crystal structures and reaction mechanisms of certain hydrolases having defined functions were investigated. However, our knowledge of the biochemical properties of most hydrolases still remains fragmentary, and that of their cellular functions remains elusive. Owing to redundancy, PG hydrolases far outnumber the enzymes of PG biosynthesis. The presence of the two sets of enzymes acting on the PG bonds raises the question of their functional correlations. It is difficult to understand why E. coli keeps such a large set of PG hydrolases. The subtle differences in substrate specificities between the isoenzymes of each family certainly reflect a variety of as-yet-unidentified physiological functions. Their study will be a far more difficult challenge than that of the steps of the PG biosynthesis pathway. PMID:22126997

  1. [The effects of TorR protein on initiation of DNA replication in Escherichia coli].

    Science.gov (United States)

    Yuan, Yao; Jiaxin, Qiao; Jing, Li; Hui, Li; Morigen, Morigen

    2015-03-01

    The two-component systems, which could sense and respond to environmental changes, widely exist in bacteria as a signal transduction pathway. The bacterial CckA/CtrA, ArcA/ArcB and PhoP/PhoQ two-component systems are associated with initiation of DNA replication and cell division, however, the effects of the TorS/TorR system on cell cycle and DNA replication remains unknown. The TorS/TorR system in Escherichia coli can sense changes in trimethylamine oxide (TMAO) concentration around the cells. However, it is unknown if it also affects initiation of DNA replication. We detected DNA replication patterns in ΔtorS and ΔtorR mutant strains by flow cytometry. We found that the average number of replication origins (oriCs) per cell and doubling time in ΔtorS mutants were the same while the average number of oriCs in ΔtorR mutants was increased compared with that in wild-type cells. These results indicated that absence of TorR led to an earlier initiation of DNA replication than that in wild-type cells. Strangely, neither overexpression of TorR nor co-expression of TorR and TorS could restore ΔtorR mutant phenotype to the wild type. However, overexpression of SufD in both wild type and ΔtorR mutants promoted initiation of DNA replication, while mutation of SufD delayed it in ΔtorR mutants. Thus, TorR may affect initiation of DNA replication indirectly through regulating gene expression of sufD.

  2. [Effect of Pseudomonas aeruginosa exometabolites on planktonic and biofilm cultures of Escherichia coli].

    Science.gov (United States)

    Kuznetsova, M V; Karpunina, T I; Maslennikova, I L; Nesterova, L Iu; Demakov, V A

    2012-01-01

    Study the effect of P. aeruginosa exometabolites on planktonic and biofilm cultures of bioluminescent E. coli strain. E. coli K12 TG1 (pF1 lux+ Ap(r)) recombinant bioluminescent strain, P. aeruginosa ATCC 27853 reference strain and 2 nosocomial isolates were used. Pyocyanin and pyoverdin content in supernatant of P. aeruginosa over-night cultures was evaluated according to E. Deziel et al. (2001). Planktonic and biofilm cultures of E. coli were obtained in 96-well plates (LB, statically, 37 degrees C), optical density of plankton, film biomass (OD600, OD580) and bioluminescence in plankton and biofilm were evaluated in microplate reader Infiniti M200 (Tecan, Austria). P. aeruginosa exometabolites increased the duration of lag-phase in E. coli, and short term exposition inhibited luminescence of planktonic cells. These effects are determined by bactericidal action ofpyocyanin and pyoverdin. Supernatants ofover-night cultures of P. aeruginosa inhibit formation of biofilm and disrupt the formed biofilm of E. coli. Effect of pyocyanin and pyoverdin on these processes is not established, other factors may have higher significance. Bioluminescence of E. coli K12 TGI that reflects the energetic status of the cell allows to evaluate and prognose the character of coexistence of P. aeruginosa in combined with E. coli planktonic and biofilm culture.

  3. Effect of Antimicrobial Dosage Regimen on Salmonella and Escherichia coli Isolates from Feeder Swine▿

    Science.gov (United States)

    Wagner, Bruce A.; Straw, Barbara E.; Fedorka-Cray, Paula J.; Dargatz, David A.

    2008-01-01

    A body of evidence exists that suggests that antimicrobial use in food animals leads to resistance in both pathogenic and commensal bacteria. This study focused on the impact of three different antimicrobial regimes (low-level continuous, pulse, and no antimicrobial) for two antimicrobials (chlortetracycline and tylosin) on the presence of Salmonella spp. and on the prevalence of antimicrobial resistance of both Salmonella spp. and nonspecific Escherichia coli in fecal samples from feeder swine. The prevalence of fecal samples positive for Salmonella spp. significantly decreased between the samples taken at feeder placement compared to samples taken when the animals were close to market weight. Differences in resistance of Salmonella spp. did not appear to be influenced by dosing treatment including the control. Analysis of antimicrobial resistance examining both susceptibility and resistance, as well as MIC outcomes, demonstrated that only resistance to cephalothin increased in E. coli under the pulse chlortetracycline treatment. These results suggest that the dosing regimes examined in this study did not lead to an increase in either the prevalence of Salmonella spp. or the prevalence of antimicrobial resistance in isolates of Salmonella spp. or E. coli. PMID:18223115

  4. The attenuation effect of UVc radiation doses in gram-negative bacteria (Brucella, Yersinia, Escherichia coli)

    International Nuclear Information System (INIS)

    Al-Mariri, A.

    2007-01-01

    The gram-negative bacteria Yersinia enterocolitica sero group O:3 and O:9, and Brucella (Melitensis and abortus) together with Escherichia coli (O:157, DH5alpha-pEt15b), were investigated to evaluate their susceptibility to UV radiation at 254 nm. If the dose of UVc was 18.7 mW/cm2, the time required for inactivation of Y. enterocolitica and E. coli DH5alpha-pEt15b and O:157 was 240s and 360s in the dark and light respectively. Where if the dose was 19.5 mW/cm2, the time required was 60s in the dark and 120s in light respectively. The time required for inactivation of Brucella strains (melitensis and abortus) if the dose was 18.7 mW/cm2 was 240s in both dark and light, whereas it was 120s (dark) and 240s (light) respectively, when the dose was 19.5 mW/cm2. Using E. coli O:157 as control, it appears that Y. enterocolitica sero group O:3 and O:9 and vaccinal strains of Brucella (Rev. 1 and S19) are more sensitive to UV than wild Brucella strains. No relation was found between the sensitivity of Y. enterocolitica to UV and the presence or absence of a pYV+ virulence plasmid. (author)

  5. The attenuation effect of UVc radiation doses in gram-negative bacteria (Brucella, Yersinia, Escherichia coli)

    International Nuclear Information System (INIS)

    Al-Mariri, A.

    2006-06-01

    The gram-negative bacteria Yersinia enterocolitica sero group O:3 and O:9, and Brucella (Melitensis and abortus) together with Escherichia coli (O:157, DH5α-pEt15b), were investigated to evaluate their susceptibility to UV radiation at 254 nm. If the dose of UVc was 18.7 mW/cm 2 , the time required for inactivation of Y. enterocolitica and E. coli DH5α-pEt15b and O:157 was 240s and 360s in the dark and light respectively; where if the dose was 19.5 mW/cm 2 , the time required was 60s in the dark and 120s in light respectively. The time required for inactivation of Brucella strains (melitensis and abortus) if the dose was 18.7 mW/cm 2 was 240s in both dark and light, whereas it was 120s(dark) and 240s (light) respectively, when the dose was 19.5 mW/cm 2 . Using E. coli O:157 as control, it appears that Y. enterocolitica sero group O:3 and O:9 and vaccinal strains of Brucella (Rev. 1 and S19) are more sensitive to UV than wild Brucella strains. No relation was found between the sensitivity of Y. enterocolitica to UV and the presence or absence of a pYV + virulence plasmid. (author)

  6. Photoinactivation of mcr-1 positive Escherichia coli

    Science.gov (United States)

    Caires, C. S. A.; Leal, C. R. B.; Rodrigues, A. C. S.; Lima, A. R.; Silva, C. M.; Ramos, C. A. N.; Chang, M. R.; Arruda, E. J.; Oliveira, S. L.; Nascimento, V. A.; Caires, A. R. L.

    2018-01-01

    The emergence of plasmid-mediated colistin resistance in Enterobacteriaceae, mostly in Escherichia coli due to the mcr-1 gene, has revealed the need to develop alternative approaches in treating mcr-1 positive bacterial infections. This is because colistin is a broad-spectrum antibiotic and one of the ‘last-resort’ antibiotics for multidrug resistant bacteria. The present study evaluated for the first time, to the best of our knowledge, the efficacy of photoinactivation processes to kill a known mcr-1 positive E. coli strain. Eosin methylene-blue (EMB) was investigated as a photoantimicrobial agent for inhibiting the growth of a mcr-1 positive E. coli strain obtained from a patient with a diabetic foot infection. The photoantimicrobial activity of EMB was also tested in a non-multidrug resistant E. coli strain. The photoinactivation process was tested using light doses in the 30-45 J cm-2 range provided by a LED device emitting at 625 nm. Our findings demonstrate that a mcr-1 positive E. coli strain is susceptible to photoinactivation. The results show that the EMB was successfully photoactivated, regardless of the bacterial multidrug resistance; inactivating the bacterial growth by oxidizing the cells in accordance with the generation of the oxygen reactive species. Our results suggest that bacterial photoinactivation is an alternative and effective approach to kill mcr-1 positive bacteria.

  7. (ESBL) producing Escherichia coli and Klebsiella pneumoniae

    African Journals Online (AJOL)

    use

    2011-11-21

    Nov 21, 2011 ... the most common serious bacterial infections in infants ... UTI is a common cause of morbidity .... of ESBL and non-ESBL producing Escherichia coli and Klebsiella pneumonia. ... in hospital and community acquired infections.

  8. Characterization of Escherichia coli Phylogenetic Groups ...

    African Journals Online (AJOL)

    tract infection (UTI), bacteremia, pneumonia, soft-tissue infection, and ... Keywords: Drug resistance, Escherichia coli, Extraintestinal infections, Polymerase chain reaction, .... gynecology, 12 from orthopedics and 5 from pediatrics units.

  9. Effects of thermosonication on the fate of Escherichia coli O157:H7 and Salmonella Enteritidis in mango juice.

    Science.gov (United States)

    Kiang, W-S; Bhat, R; Rosma, A; Cheng, L-H

    2013-04-01

    In this study, the effects of thermosonication and thermal treatment on Escherichia coli O157:H7 and Salmonella Enteritidis in mango juice were investigated at 50 and 60°C. Besides, nonlethal injury of Salm. Enteritidis after both treatments was also examined. The highest inactivation was attained with thermosonication at 60°C. The inactivation rate was different for both pathogens, and Salm. Enteritidis was found to be more sensitive to thermosonication than E. coli O157:H7. Salmonella Enteritidis was recovered in all treated samples, except those subjected to more than 5-min thermosonication at 60°C. It was found that the introduction of high-intensity ultrasound enhanced the inactivation of pathogens compared to thermal treatment alone. On the other hand, Salm. Enteritidis was detected in a number of samples following incubation in universal pre-enrichment broth, but no growth was detected after incubation in mango juice. Fruit juices are commonly heat treated to inactivate micro-organisms and enzymes. However, excessive heat treatments may result in undesirable changes in juice quality. Treatment by power ultrasound, a nonthermal technology, may be an alternative processing technique to pasteurize fruit juices. This study highlights the effectiveness of thermosonication in inactivating Escherichia coli O157:H7 and Salmonella Enteritidis in mango juice. © 2012 The Society for Applied Microbiology.

  10. The enhanced effects of antibiotics irradiated of extremely high frequency electromagnetic field on Escherichia coli growth properties.

    Science.gov (United States)

    Torgomyan, Heghine; Trchounian, Armen

    2015-01-01

    The effects of extremely high frequency electromagnetic irradiation and antibiotics on Escherichia coli can create new opportunities for applications in different areas—medicine, agriculture, and food industry. Previously was shown that irradiated bacterial sensitivity against antibiotics was changed. In this work, it was presented the results that irradiation of antibiotics and then adding into growth medium was more effective compared with non-irradiated antibiotics bactericidal action. The selected antibiotics (tetracycline, kanamycin, chloramphenicol, and ceftriaxone) were from different groups. Antibiotics irradiation was performed with low intensity 53 GHz frequency during 1 h. The E. coli growth properties—lag-phase duration and specific growth rate—were markedly changed. Enhanced bacterial sensitivity to irradiated antibiotics is similar to the effects of antibiotics of higher concentrations.

  11. Transcriptomic analysis displays the effect of (-)-roemerine on the motility and nutrient uptake in Escherichia coli.

    Science.gov (United States)

    Ayyildiz, Dilara; Arga, Kazim Yalcin; Avci, Fatma Gizem; Altinisik, Fatma Ece; Gurer, Caglayan; Gulsoy Toplan, Gizem; Kazan, Dilek; Wozny, Katharina; Brügger, Britta; Mertoglu, Bulent; Sariyar Akbulut, Berna

    2017-08-01

    Among the different families of plant alkaloids, (-)-roemerine, an aporphine type, was recently shown to possess significant antibacterial activity in Escherichia coli. Based on the increasing demand for antibacterials with novel mechanisms of action, the present work investigates the potential of the plant-derived alkaloid (-)-roemerine as an antibacterial in E. coli cells using microarray technology. Analysis of the genome-wide transcriptional reprogramming in cells after 60 min treatment with 100 μg/mL (-)-roemerine showed significant changes in the expression of 241 genes (p value 2). Expression of selected genes was confirmed by qPCR. Differentially expressed genes were classified into functional categories to map biological processes and molecular pathways involved. Cellular activities with roles in carbohydrate transport and metabolism, energy production and conversion, lipid transport and metabolism, amino acid transport and metabolism, two-component signaling systems, and cell motility (in particular, the flagellar organization and motility) were among metabolic processes altered in the presence of (-)-roemerine. The down-regulation of the outer membrane proteins probably led to a decrease in carbohydrate uptake rate, which in turn results in nutrient limitation. Consequently, energy metabolism is slowed down. Interestingly, the majority of the expressional alterations were found in the flagellar system. This suggested reduction in motility and loss in the ability to form biofilms, thus affecting protection of E. coli against host cell defense mechanisms. In summary, our findings suggest that the antimicrobial action of (-)-roemerine in E. coli is linked to disturbances in motility and nutrient uptake.

  12. Generic Escherichia coli Contamination of Spinach at the Preharvest Stage: Effects of Farm Management and Environmental Factors

    Science.gov (United States)

    Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Jun, Mikyoung; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Ivanek, Renata

    2013-01-01

    The objective of this study was to determine the effects of farm management and environmental factors on preharvest spinach contamination with generic Escherichia coli as an indicator of fecal contamination. A repeated cross-sectional study was conducted by visiting spinach farms up to four times per growing season over a period of 2 years (2010 to 2011). Spinach samples (n = 955) were collected from 12 spinach farms in Colorado and Texas as representative states of the Western and Southwestern United States, respectively. During each farm visit, farmers were surveyed about farm-related management and environmental factors using a questionnaire. Associations between the prevalence of generic E. coli in spinach and farm-related factors were assessed by using a multivariable logistic regression model including random effects for farm and farm visit. Overall, 6.6% of spinach samples were positive for generic E. coli. Significant risk factors for spinach contamination with generic E. coli were the proximity (within 10 miles) of a poultry farm, the use of pond water for irrigation, a >66-day period since the planting of spinach, farming on fields previously used for grazing, the production of hay before spinach planting, and the farm location in the Southwestern United States. Contamination with generic E. coli was significantly reduced with an irrigation lapse time of >5 days as well as by several factors related to field workers, including the use of portable toilets, training to use portable toilets, and the use of hand-washing stations. To our knowledge, this is the first report of an association between field workers' personal hygiene and produce contamination with generic E. coli at the preharvest level. Collectively, our findings support that practice of good personal hygiene and other good farm management practices may reduce produce contamination with generic E. coli at the preharvest level. PMID:23666336

  13. Generic Escherichia coli contamination of spinach at the preharvest stage: effects of farm management and environmental factors.

    Science.gov (United States)

    Park, Sangshin; Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Jun, Mikyoung; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Ivanek, Renata

    2013-07-01

    The objective of this study was to determine the effects of farm management and environmental factors on preharvest spinach contamination with generic Escherichia coli as an indicator of fecal contamination. A repeated cross-sectional study was conducted by visiting spinach farms up to four times per growing season over a period of 2 years (2010 to 2011). Spinach samples (n = 955) were collected from 12 spinach farms in Colorado and Texas as representative states of the Western and Southwestern United States, respectively. During each farm visit, farmers were surveyed about farm-related management and environmental factors using a questionnaire. Associations between the prevalence of generic E. coli in spinach and farm-related factors were assessed by using a multivariable logistic regression model including random effects for farm and farm visit. Overall, 6.6% of spinach samples were positive for generic E. coli. Significant risk factors for spinach contamination with generic E. coli were the proximity (within 10 miles) of a poultry farm, the use of pond water for irrigation, a >66-day period since the planting of spinach, farming on fields previously used for grazing, the production of hay before spinach planting, and the farm location in the Southwestern United States. Contamination with generic E. coli was significantly reduced with an irrigation lapse time of >5 days as well as by several factors related to field workers, including the use of portable toilets, training to use portable toilets, and the use of hand-washing stations. To our knowledge, this is the first report of an association between field workers' personal hygiene and produce contamination with generic E. coli at the preharvest level. Collectively, our findings support that practice of good personal hygiene and other good farm management practices may reduce produce contamination with generic E. coli at the preharvest level.

  14. Effects of water chemistry on the dissolution of ZnO nanoparticles and their toxicity to Escherichia coli

    International Nuclear Information System (INIS)

    Li Mei; Lin Daohui; Zhu Lizhong

    2013-01-01

    The dissolution of ZnO nanoparticles (nano-ZnO) plays an important role in the toxicity of nano-ZnO to the aquatic organisms. The effects of water chemistry such as pH, ionic components, and dissolved organic matter (DOM) on the dissolution of nano-ZnO and its toxicity to Escherichia coli (E. coli) were investigated in synthetic and natural water samples. The results showed that the toxicity of nano-ZnO to E. coli depended on not only free Zn 2+ but also the coexisting cations which could reduce the toxicity of Zn 2+ . Increasing solution pH, HPO 4 2− , and DOM reduced the concentration of free Zn 2+ released from nano-ZnO, and thus lowered the toxicity of nano-ZnO. In addition, both Ca 2+ and Mg 2+ dramatically reduced the toxicity of Zn 2+ to E. coli. These results highlight the importance of water chemistry on the toxicity evaluation of nano-ZnO in natural waters. - Highlights: ► The effects of water chemistry on the toxicity of nano-ZnO were investigated. ► Increasing solution pH, HPO 4 2− , and DOM reduced nano-ZnO toxicity to E. coli. ► Ca 2+ and Mg 2+ could dramatically reduce the toxicity of nano-ZnO to E. coli. ► Free Zn 2+ ions and water hardness together controlled nano-ZnO toxicity in waters. - The toxicity of nano-ZnO to E. coli depended on not only free Zn 2+ but also Ca 2+ and Mg 2+ which could reduce the toxicity of Zn 2+ .

  15. Expression of green fluorescent protein (GFPuv) in Escherichia coli ...

    African Journals Online (AJOL)

    Administrator

    The recombinant green fluorescent protein (GFPuv) was expressed by transformed cells of Escherichia coli DH5-α grown in LB/amp broth at 37oC, for 8 h and 24 h. To evaluate the effectiveness of different parameters to improve the expression of GFPuv by E. coli, four variable culturing conditions were set up for assays by ...

  16. Effects of Aronia melanocarpa Constituents on Biofilm Formation of Escherichia coli and Bacillus cereus

    Directory of Open Access Journals (Sweden)

    Marie Bräunlich

    2013-12-01

    Full Text Available Many bacteria growing on surfaces form biofilms. Adaptive and genetic changes of the microorganisms in this structure make them resistant to antimicrobial agents. Biofilm-forming organisms on medical devices can pose serious threats to human health. Thus, there is a need for novel prevention and treatment strategies. This study aimed to evaluate the ability of Aronia melanocarpa extracts, subfractions and compounds to prevent biofilm formation and to inhibit bacterial growth of Escherichia coli and Bacillus cereus in vitro. It was found that several aronia substances possessed anti-biofilm activity, however, they were not toxic to the species screened. This non-toxic inhibition may confer a lower potential for resistance development compared to conventional antimicrobials.

  17. Rare codons effect on expression of recombinant gene cassette in Escherichia coli BL21(DE3

    Directory of Open Access Journals (Sweden)

    Aghil Esmaeili-Bandboni

    2017-11-01

    Full Text Available Objective: To demonstrate the sensitivity of expression of fusion genes to existence of a large number of rare codons in recombinant gene sequenced. Methods: Primers for amplification of cholera toxin B, Shiga toxin B and gfp genes were designed by Primer3 software and synthesized. All of these 3 genes were cloned. Then the genes were fused together by restriction sites and enzymatic method. Two linkers were used as a flexible bridge in connection of these genes. Results: Cloning and fusion of cholera toxin B, Shiga toxin B and gfp genes were done correctly. After that, expression of the recombinant gene construction was surveyed. Conclusions: According to what was seen, because of the accumulation of 12 rare codons of Shiga toxin B and 19 rare codons of cholera toxin B in this gene cassette, the expression of the recombinant gene cassette, in Escherichia coli BL21, failed.

  18. Antimicrobial Effect of Escherichia Coli on Essential Oils Derived from Romanian Aromatic Plants

    Directory of Open Access Journals (Sweden)

    Şandru Daniela Maria

    2015-07-01

    Full Text Available This paper investigates the antimicrobial action of Escherichia coli ATCCR CRM-8739TM on the following essential oils: Teucrium marum, Pinus sylwestris, Thymus vulgaris, Salviae aethedaroleum, Cinnamomum aromaticum, Hippophae rhamnoides, Lavandula angustifolia, Abies alba, Zingiber officinale, Anethum graveolens, Coriandrum sativum, Origanum vulgare, extracted industrialy from romanian plants, using the diffusion disc method. The most intense activity was observed at the essential oil of Cinnamomum aromaticum (cinnamon and the mildest activity was observed at Zingiber officinale (ginger. Many of the essential oils tested exhibited moderate antimicrobial activity, as Teucrium marum, Thymus vulgaris, Hippophae rhamnoides, Lavandula angustifolia,Coriandrum sativum. The lowest antibacterial activity was exhibited on Pinus sylwestris, Salviae aethedaroleum, Zingiber officinale and Anethum graveolens.

  19. Effect of surface roughness on performance of magnetoelastic biosensors for the detection of Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Possan, A.L. [Centro de Ciências Exatas e Tecnologia, Universidade de Caxias do Sul, Caxias do Sul, RS (Brazil); Menti, C. [Instituto de Biotecnologia, Universidade de Caxias do Sul, Caxias do Sul, RS (Brazil); Beltrami, M. [Centro de Ciências Exatas e Tecnologia, Universidade de Caxias do Sul, Caxias do Sul, RS (Brazil); Santos, A.D. [Instituto de Física, Universidade de São Paulo, São Paulo, SP (Brazil); Roesch-Ely, M. [Instituto de Biotecnologia, Universidade de Caxias do Sul, Caxias do Sul, RS (Brazil); Missell, F.P., E-mail: fmissell@yahoo.com [Centro de Ciências Exatas e Tecnologia, Universidade de Caxias do Sul, Caxias do Sul, RS (Brazil)

    2016-01-01

    Escherichia coli are bacteria that must be controlled in the food industry and the hospital sector. Magnetoelastic biosensors offer the promise of rapid identification of these and other harmful antigens. In this work, strips of amorphous Metglas 2826MB3 were cut to size (5 mm × 1 mm) with a microdicing saw and were then coated with thin layers of Cr and Au, as verified by Rutherford backscattering spectroscopy (RBS). Several sensor surfaces were studied: 1) as-cast strip, wheel side; 2) as-cast strip, free surface; and 3) thinned and polished surface. A layer of cystamine was applied to the Au-covered magnetoelastic substrate, forming a self-assembled monolayer (SAM), followed by antibodies, using a modified Hermanson protocol. The cystamine layer growth was verified by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The biosensors were exposed to solutions of bacteria and the resonant frequency of the sensors was measured with an impedance analyzer for times up to 100 min. Reductions in the resonant frequency, corresponding to bacteria capture, were measured after optimizing the signal amplitude. For times up to 40 min, high capture rates were observed and thereafter saturation occurred. Saturation values of the frequency shifts were compared with the number of bacteria observed on the sensor using fluorescence microscopy. Parameters associated with capture kinetics were studied for different sensor surfaces. The rough surfaces were found to show a faster response, while the thinned and polished sensors showed the largest frequency shift. - Highlights: • Magnetoelastic biosensors to capture Escherichia coli were produced. • Surface roughness of biosensors was varied in the range R{sub a} = 0.3–0.52 μm. • Rough surfaces show faster response, polished surfaces have larger frequency shift.

  20. Effect of surface roughness on performance of magnetoelastic biosensors for the detection of Escherichia coli

    International Nuclear Information System (INIS)

    Possan, A.L.; Menti, C.; Beltrami, M.; Santos, A.D.; Roesch-Ely, M.; Missell, F.P.

    2016-01-01

    Escherichia coli are bacteria that must be controlled in the food industry and the hospital sector. Magnetoelastic biosensors offer the promise of rapid identification of these and other harmful antigens. In this work, strips of amorphous Metglas 2826MB3 were cut to size (5 mm × 1 mm) with a microdicing saw and were then coated with thin layers of Cr and Au, as verified by Rutherford backscattering spectroscopy (RBS). Several sensor surfaces were studied: 1) as-cast strip, wheel side; 2) as-cast strip, free surface; and 3) thinned and polished surface. A layer of cystamine was applied to the Au-covered magnetoelastic substrate, forming a self-assembled monolayer (SAM), followed by antibodies, using a modified Hermanson protocol. The cystamine layer growth was verified by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The biosensors were exposed to solutions of bacteria and the resonant frequency of the sensors was measured with an impedance analyzer for times up to 100 min. Reductions in the resonant frequency, corresponding to bacteria capture, were measured after optimizing the signal amplitude. For times up to 40 min, high capture rates were observed and thereafter saturation occurred. Saturation values of the frequency shifts were compared with the number of bacteria observed on the sensor using fluorescence microscopy. Parameters associated with capture kinetics were studied for different sensor surfaces. The rough surfaces were found to show a faster response, while the thinned and polished sensors showed the largest frequency shift. - Highlights: • Magnetoelastic biosensors to capture Escherichia coli were produced. • Surface roughness of biosensors was varied in the range R a = 0.3–0.52 μm. • Rough surfaces show faster response, polished surfaces have larger frequency shift.

  1. Antimicrobial resistance among commensal Escherichia coli from ...

    African Journals Online (AJOL)

    Commensal bacteria contribute to the distribution and persistence of antimicrobial resistance in the environment. This study monitored antimicrobial resistance in commensal Escherichia coli from the faeces of on-farm and slaughter cattle and beef. A total of 342 (89.5%) E. coli isolates were obtained from 382 samples.

  2. Characterization of Escherichia coli Phylogenetic Groups ...

    African Journals Online (AJOL)

    Background: Escherichia coli strains mainly fall into four phylogenetic groups (A, B1, B2, and D) and that virulent extra‑intestinal strains mainly belong to groups B2 and D. Aim: The aim was to determine the association between phylogenetic groups of E. coli causing extraintestinal infections (ExPEC) regarding the site of ...

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

    Science.gov (United States)

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

    2015-11-01

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

  4. Strategies for Protein Overproduction in Escherichia coli.

    Science.gov (United States)

    Mott, John E.

    1984-01-01

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

  5. Escherichia coli survival in waters: Temperature dependence

    Science.gov (United States)

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

  6. Comparison of 61 Sequenced Escherichia coli Genomes

    DEFF Research Database (Denmark)

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

    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. Sixty-one publically available E. coli and Shigella spp. sequenced genomes are compared, using basic methods to produce phylogenetic and proteomics...

  7. Antimicrobial resistance among commensal Escherichia coli from ...

    African Journals Online (AJOL)

    user1

    2012-07-19

    Jul 19, 2012 ... Commensal bacteria contribute to the distribution and persistence of antimicrobial resistance in the environment. This study monitored antimicrobial resistance in commensal Escherichia coli from the faeces of on-farm and slaughter cattle and beef. A total of 342 (89.5%) E. coli isolates were obtained.

  8. Fimbrial adhesins from extraintestinal Escherichia coli

    DEFF Research Database (Denmark)

    Klemm, Per; Hancock, Viktoria; Schembri, Mark A.

    2010-01-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) represent an important subclass of E. coli that cause a wide spectrum of diseases in human and animal hosts. Fimbriae are key virulence factors of ExPEC strains. These long surface located rod-shaped organelles mediate receptor-specific attachment...

  9. lactamase in clinical isolates of Escherichia coli

    African Journals Online (AJOL)

    Jane

    2011-08-22

    Aug 22, 2011 ... The beta lactamase enzyme producing E. coli, resistant to β-lactam antibiotics, created many problems ... Key words: Escherichia coli, β-lactamase enzymes, TEM-type extended spectrum ... difficulties in treatment using antibiotics that are currently ... and chloramphenicol (30 µg) (Mast Diagnostics Ltd., UK).

  10. 99mTechnetium labelled Escherichia coli

    International Nuclear Information System (INIS)

    Diniz, S.O.F.; Cardoso, V.N.; Resende, B.M.; Nunan, E.A.; Simal, C.J.R.

    1999-01-01

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

  11. Anti-aggregatory effect of cyclodextrins in the refolding process of recombinant growth hormones from Escherichia coli inclusion bodies

    DEFF Research Database (Denmark)

    Bajorunaite, Egle; Cirkovas, Andrejus; Radzevicius, Kostas

    2009-01-01

    Cyclodextrins with different ring size and ring substituents were tested for recombinant mink and porcine growth hormones aggregation suppression in the refolding process from Escherichia coli inclusion bodies. Methyl-β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin show a positive effect...... on the aggregation suppression of both proteins. The influence of different methyl-β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin concentrations on the renaturation yield of both growth hormones was investigated. Moreover, methyl-β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin suppress not only folding...

  12. ANALISIS CEMARAN BAKTERI Escherichia coli ANALISIS CEMARAN BAKTERI Escherichia coli ANALISIS CEMARAN BAKTERI Escherichia coli

    OpenAIRE

    ANGGREINI, RAHAYU

    2015-01-01

    2015 RAHAYU ANGGREINI coli Penelitian ini bertujuan untuk melakukan identifikasi cemaran bakteri E. coli O157:H7 pada daging sapi di kota Makassar. Sampel pada penelitian ini sebanyak 72 sampel Kata Kunci : Daging sapi, pasar tradisional, E. coli, E. coli O157:H7, kontaminasi bakteri, identifikasi E. coli O157:H7.

  13. In vitro antibacterial effect of Withania somnifera root extract on Escherichia coli

    Science.gov (United States)

    Kumari, Mamta; Gupta, R. P.

    2015-01-01

    Aim: The aim was to investigate antibacterial activity of Withania somnifera (Ashwagandha), an Indian traditional medicinal plant against Escherichia coli O78, a pathogenic strain. Materials and Methods: Two-fold serial dilutions of 20% aqueous W. somnifera root (WSR) extract were inoculated with E. coli O78 @ 1*107 colony forming units grown in nutrient broth. Following inoculation, turbidity optical density was measured by spectrophotometer at 600 nm in all the tubes at 0, 2, 4, 6 and 8 h of incubation at 37°C. Result: The results revealed that the maximum inhibition of bacterial growth was observed at 1:8 dilution of WSR extract. The highest dilution of the extract that showed inhibited growth of the test organism when compared with control was 1:16. Therefore, the minimum inhibitory concentration of aqueous extract of WSR is 1:16. Conclusion: It is concluded that WSR possessed good antibacterial activity, confirming the great potential of bioactive compounds and its rationalizing use in health care. PMID:27046997

  14. Effects of in-feed chlortetracycline prophylaxis of beef cattle on animal health and antimicrobial-resistant Escherichia coli

    Science.gov (United States)

    Concerns have been raised that in-feed chlortetracycline (CTC) may increase antimicrobial resistance (AMR), specifically tetracycline-resistant (TETr) Escherichia coli, and third-generation cephalosporin-resistant (3GCr) E. coli. We evaluated the impact of a 5-day in-feed CTC prophylaxis on animal h...

  15. Investigation of Combination Effect of Magnesium Oxide and Iron Oxide Nanoparticles on the Growth And Morphology of the Bacteria Staphylococcus Aureus and Escherichia Coli in Juice

    Directory of Open Access Journals (Sweden)

    mahdi torabi zarchi

    2017-02-01

    Full Text Available Introduction: Nanoparticles (NPs are one of the antibacterial substances, among them nanoparticles type MgO and Fe2O3 are less toxic to mammalian cells. So, the aim of this study was investigation of combination effects of iron oxide and magnesium oxide nanoparticles on the growth of Staphylococcus aureus and Escherichia coli (E.coli to achieve the optimum combination of nanoparticles inhibit the growth of Staphylococcus aureus and Escherichia coli in food (juice. Methods: In this experimental research, the effect of MgO and Fe2O3 Nanoparticles compound on Staphylococcus aureus and Escherichia coli bacteria in liquid environment was investigated, and then their effect was investigated separately in juices of carrot, pomegranate and apple via colony count approach. Also, scanning electron microscopy was used to characterize the morphological changes of Staphylococcus aureus and Escherichia coli after antimicrobial treatments. The results of the research were analyzed using one way ANNOVA. Results: The results of the research indicated that in liquid medium, these nanoparticles lead to reduce the growth of both bacteria. compound of 1.5Mg+0.5Fe2O3 was introduced as the most appropriate antibacterial compounds; Staphylococcus aureus sensitivity to Escherichia coli was higher against nanoparticles. The findings of research about the juices revealed that the combined effect of nanoparticles reduced the growth of both bacteria. the combined effect of Fe2o3 and MgO nanoparticles treatments distorted and damaged the cell membrane, resulting in a leakage of intracellular contents and eventually the death of bacterial cells. Conclusion: Nanoparticles in the allowed concentrations have significant effect on Staphylococcus aureus and Escherichia coli bacteria.

  16. Effects of high hydrostatic pressure and temperature increase on Escherichia coli spp. and pectin methyl esterase inactivation in orange juice.

    Science.gov (United States)

    Torres, E F; González-M, G; Klotz, B; Rodrigo, D

    2016-03-01

    The aim of this study was to evaluate the effect of high hydrostatic pressure treatment combined with moderate processing temperatures (25 ℃-50 ℃) on the inactivation of Escherichia coli O157: H7 (ATCC 700728), E. coli K12 (ATCC 23716), and pectin methyl esterase in orange juice, using pressures of 250 to 500 MPa with times ranging between 1 and 30 min. Loss of viability of E. coli O157:H7 increased significantly as pressure and treatment time increased, achieving a 6.5 log cycle reduction at 400 MPa for 3 min at 25 ℃ of treatment. With regard to the inactivation of pectin methyl esterase, the greatest reduction obtained was 90.05 ± 0.01% at 50 ℃ and 500 MPa of pressure for 15 min; therefore, the pectin methyl esterase enzyme was highly resistant to the treatments by high hydrostatic pressure. The results obtained in this study showed a synergistic effect between the high pressure and moderate temperatures in inactivating E. coli cells. © The Author(s) 2016.

  17. Engineering Escherichia coli for methanol conversion.

    Science.gov (United States)

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

    2015-03-01

    Methylotrophic bacteria utilize methanol and other reduced one-carbon compounds as their sole source of carbon and energy. For this purpose, these bacteria evolved a number of specialized enzymes and pathways. Here, we used a synthetic biology approach to select and introduce a set of "methylotrophy genes" into Escherichia coli based on in silico considerations and flux balance analysis to enable methanol dissimilation and assimilation. We determined that the most promising approach allowing the utilization of methanol was the implementation of NAD-dependent methanol dehydrogenase and the establishment of the ribulose monophosphate cycle by expressing the genes for hexulose-6-phosphate synthase (Hps) and 6-phospho-3-hexuloisomerase (Phi). To test for the best-performing enzymes in the heterologous host, a number of enzyme candidates from different donor organisms were selected and systematically analyzed for their in vitro and in vivo activities in E. coli. Among these, Mdh2, Hps and Phi originating from Bacillus methanolicus were found to be the most effective. Labeling experiments using (13)C methanol with E. coli producing these enzymes showed up to 40% incorporation of methanol into central metabolites. The presence of the endogenous glutathione-dependent formaldehyde oxidation pathway of E. coli did not adversely affect the methanol conversion rate. Taken together, the results of this study represent a major advancement towards establishing synthetic methylotrophs by gene transfer. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  18. Effects of administration of four different doses of Escherichia coli phytase on femur properties of 16-week-old turkeys.

    Science.gov (United States)

    Tatara, Marcin R; Krupski, Witold; Kozłowski, Krzysztof; Drażbo, Aleksandra; Jankowski, Jan

    2015-03-18

    The enzyme phytase is able to initiate the release of phosphates from phytic acid, making it available for absorption within gastrointestinal tract and following utilization. The aim of the study was to determine effects of Escherichia coli phytase administration on morphological, densitometric and mechanical properties of femur in 16-week-old turkeys. One-day-old BUT Big-6 males were assigned to six weight-matched groups. Turkeys receiving diet with standard phosphorus (P) and calcium (Ca) content belonged to the positive control group (Group I). Negative control group (Group II) consisted of birds fed diet with lowered P and Ca content. Turkeys belonging to the remaining groups have received the same diet as group II but enriched with graded levels of Escherichia coli phytase: 125 (Group III), 250 (Group IV), 500 (Group V) and 1000 (Group VI) FTU/kg. At the age of 112 days of life, the final body weights were determined and the turkeys were sacrificed to obtain right femur for analyses. Geometric and densitometric properties of femur were determined using quantitative computed tomography (QCT) technique, while mechanical evaluation was performed in three-point bending test. Phytase administration increased cross-sectional area, second moment of inertia, mean relative wall thickness, cortical bone mineral density and maximum elastic strength decreasing cortical bone area of femur (P phytase administration on geometric, densitometric and mechanical properties of femur were observed in turkeys receiving 125 and 250 FTU/kg of the diet. Phytase administration at the dosages of 500 and 1000 FTU/kg of the diet improved the final body weight in turkeys. The results obtained in this study indicate a possible practical application of Escherichia coli phytase in turkey feeding to improve skeletal system properties and function.

  19. Effectiveness of Active Packaging on Control of Escherichia Coli O157:H7 and Total Aerobic Bacteria on Iceberg Lettuce.

    Science.gov (United States)

    Lu, Haixia; Zhu, Junli; Li, Jianrong; Chen, Jinru

    2015-06-01

    Contaminated leafy green vegetables have been linked to several outbreaks of human gastrointestinal infections. Antimicrobial interventions that are adoptable by the fresh produce industry for control of pathogen contamination are in great demand. This study was undertaken to evaluate the efficacy of sustained active packaging on control of Escherichia coli O157:H7 and total aerobic bacteria on lettuce. Commercial Iceberg lettuce was inoculated with a 3-strain mixture of E. coli O157:H7 at 10(2) or 10(4) CFU/g. The contaminated lettuce and un-inoculated controls were placed respectively in 5 different active packaging structures. Traditional, nonactive packaging structure was included as controls. Packaged lettuce was stored at 4, 10, or 22 °C for 3 wk and sampled weekly for the population of E. coli O157:H7 and total aerobic bacteria. Results showed that packaging structures with ClO2 generator, CO2 generator, or one of the O2 scavengers effectively controlled the growth of E. coli O157:H7 and total aerobic bacteria under all storage conditions. Packaging structure with the ClO2 generator was most effective and no E. coli O157:H7 was detected in samples packaged in this structure except for those that were inoculated with 4 log CFU/g of E. coli O157:H7 and stored at 22 °C. Packaging structures with an oxygen scavenger and the allyl isothiocyanate generator were mostly ineffective in control of the growth of the bacteria on Iceberg lettuce. The research suggests that some of the packaging structures evaluated in the study can be used to control the presence of foodborne pathogens on leafy green vegetables. © 2015 Institute of Food Technologists®

  20. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Escherichia coli serological reagents. 866.3255... coli serological reagents. (a) Identification. Escherichia coli serological reagents are devices that consist of antigens and antisera used in serological tests to identify Escherichia coli from cultured...

  1. Comparison of the effect of nalidixic acid and thymine deprivation on excision repair in Escherichia coli

    International Nuclear Information System (INIS)

    Masek, F.; Slezarikova, V.; Sedliakova, M.

    1975-01-01

    A difference was found in the extent of inhibition of thymine dimers (TT) excision in ultraviolet (UV) irradiated cells of E. coli after preirradiation depression of protein and DNA syntheses induced by a simultaneous removal of essential amino acids (AA - ) and thymine (T - ) or by the removal of essential amino acids and the addition of nalidixic acid (NAL + ). The difference was observed in both E. coli B/r Hcr + and E. coli K12 SR20 uvr + cells. The depression of DNA synthesis by nalidixic acid as an exogenous agent inhibited TT excision to a lower degree than the depression of DNA synthesis by thymine starvation. The extent of TT excision had no appreciable effect on the restoration of the sedimentation profile of a newly synthesized DNA nor on UV resistance of cells during dark repair. A DNA molecule having the size of a molecule of nonirradiated cells became synthesized while TT were still present in the DNA. (author)

  2. Effect of visible light on progressive dormancy of Escherichia coli cells during the survival process in natural fresh water

    International Nuclear Information System (INIS)

    Barcina, I.; Gonzalez, J.M.; Iriberri, J.; Egea, L.

    1989-01-01

    Some effects of visible light on the survival of Escherichia coli in waters of the Butron river were studied by comparing illuminated and nonilluminated systems. The following count methods were used: CFU on a selective medium (eosin-methylene blue agar), CFU on a medium of recuperation (Trypticase soy agar with yeast extract and glucose), number of metabolically active cells by reduction of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to INT-formazan, and total number of E. coli cells as determined by the acridine orange direct-count method. In the illuminated systems, decreases in CFU of E. coli and in the number of metabolically active cells were observed. However, no decline of the total number of E. coli cells was observed. By count methods, different stages of progressive dormancy of E. coli cells were determined to exist in illuminated systems. Culturable and recoverable cells were defined as viable cells, and metabolically active cells and morphologically intact cells were defined as somnicells. Indirect activity measurements were also done by using [14C]glucose. In illuminated systems, a decrease of glucose uptake by E. coli cells was observed throughout the experiments. The assimilated fraction of [14C]glucose decreased faster than the respired fraction in illuminated systems. The percentage of respired [14C]glucose (14CO2 production) with respect to the total glucose uptake increased throughout the experiments, and the percentage of assimilated glucose decreased. Therefore, the visible light was also responsible for an additional inhibition of biosynthetic processes

  3. An Effect of Cadmium and Lead Ions on Escherichia coli with the Cloned Gene for Metallothionein (MT-3) Revealed by Electrochemistry

    International Nuclear Information System (INIS)

    Adam, Vojtech; Chudobova, Dagmar; Tmejova, Katerina; Cihalova, Kristyna; Krizkova, Sona; Guran, Roman; Kominkova, Marketa; Zurek, Michal; Kremplova, Monika; Jimenez, Ana Maria Jimenez; Konecna, Marie

    2014-01-01

    This study was focused on the application of electrochemical methods for studying of bacterial strains Escherichia coli and Escherichia coli expressing human metallothionein gene (MT-3) before and after the application of cadmium and/or lead ions in four concentrations (25, 50, 75 and 150 μM). Bacterial strains Escherichia coli and Escherichia coli expressing human metallothionein gene (MT-3) were used like model organisms for studying of metals influence to metallothionein expression. Metallothionein was isolated using fast protein liquid chromatography and quantified by electrochemical methods. The occurrence of metallothionein in E.coli was confirmed by gel electrophoresis by the presence of the bands at 15 (MT dimer) and 22 kDa (MT trimer). The changes in electrochemical records due to the interactions of metallothioneins (MT-3 and MT-2A) with cadmium and lead ions showed decline of Cat2 signal of MT with the increasing interaction time because of metal ions binding to cysteines. Electrochemical determination also revealed that Cd(II) remains in E. coli cells in the higher amount than Pb (II). Opposite situation was found at E. coli–MT-3 strain. The antimicrobial effect of cadmium ions was determined by IC 50 and was statistically calculated as 39.2 and 95.5 μM for E. coli without cloned MT-3 and E. coli carrying MT-3 gene, respectively. High provided concentration IC 50 in strains after lead ions application (352.5 μM for E. coli without cloning and 207.0 μM for E. coli carrying cloned MT-3 gene) indicates lower toxicity of lead ions on bacterial strains compared to the cadmium ions

  4. Microbubble-Mediated Ultrasound Enhances the Lethal Effect of Gentamicin on Planktonic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Han-Xiao Zhu

    2014-01-01

    Full Text Available Previous research has found that low-intensity ultrasound enhanced the lethal effect of gentamicin on planktonic E. coli. We aimed to further investigate whether microbubble-mediated low-intensity ultrasound could further enhance the antimicrobial efficacy of gentamicin. The planktonic E. coli (ATCC 25922 was distributed to four different interventions: control (GCON, microbubble only (GMB, ultrasound only (GUS, and microbubble-mediated ultrasound (GMUS. Ultrasound was applied with 100 mW/cm2 (average intensity and 46.5 KHz, which presented no bactericidal activity. After 12 h, plate counting was used to estimate the number of bacteria, and bacterial micromorphology was observed with transmission electron microscope. The results showed that the viable counts of E. coli in GMUS were decreased by 1.01 to 1.42 log10 CFU/mL compared with GUS (P<0.01. The minimal inhibitory concentration (MIC of gentamicin against E. coli was 1 μg/mL in the GMUS and GUS groups, lower than that in the GCON and GMB groups (2 μg/mL. Transmission electron microscopy (TEM images exhibited more destruction and higher thickness of bacterial cell membranes in the GMUS than those in other groups. The reason might be the increased permeability of cell membranes for gentamicin caused by acoustic cavitation.

  5. Effects of Selected Egyptian Honeys on the Cellular Ultrastructure and the Gene Expression Profile of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Reham Wasfi

    Full Text Available The purpose of this study was to: (i evaluate the antibacterial activities of three Egyptian honeys collected from different floral sources (namely, citrus, clover, and marjoram against Escherichia coli; (ii investigate the effects of these honeys on bacterial ultrastructure; and (iii assess the anti-virulence potential of these honeys, by examining their impacts on the expression of eight selected genes (involved in biofilm formation, quorum sensing, and stress survival in the test organism. The minimum inhibitory concentration (MIC of the honey samples against E. coli ATCC 8739 were assessed by the broth microdilution assay in the presence and absence of catalase enzyme. Impacts of the honeys on the cellular ultrastructure and the expression profiles of the selected genes of E. coli were examined using transmission electron microscopy (TEM and quantitative real-time polymerase chain reaction (qPCR analysis, respectively. The susceptibility tests showed promising antibacterial activities of all the tested honeys against E. coli. This was supported by the TEM observations, which revealed "ghost" cells lacking DNA, in addition to cells with increased vacuoles, and/or with irregular shrunken cytoplasm. Among the tested honeys, marjoram exhibited the highest total antibacterial activity and the highest levels of peroxide-dependent activity. The qPCR analysis showed that all honey-treated cells share a similar overall pattern of gene expression, with a trend toward reduced expression of the virulence genes of interest. Our results indicate that some varieties of the Egyptian honey have the potential to be effective inhibitor and virulence modulator of E. coli via multiple molecular targets.

  6. Effect of selected aldehydes on the growth and fermentation of ethanologenic Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Zaldivar, J.; Ingram, L.O. [Univ. of Florida, Gainesville (United States). Dept. of Microbiology and Cell Science; Martinez, A. [Univ. of Florida, Gainesville (United States). Dept. of Microbiology and Cell Science]|[Univ. Nacional Autonoma de Mexico (Mexico). Inst. de Biotecnologia

    1999-10-05

    Bioethanol production from lignocellulosic raw-materials requires the hydrolysis of carbohydrate polymers into a fermentable syrup. During the hydrolysis of hemicellulose with dilute acid, a variety of toxic compounds are produced such as soluble aromatic aldehydes from lignin and furfural from pentose destruction. In this study, the authors have investigated the toxicity of representative aldehydes (furfural, 5-hydroxymethlyfurfural, 4-hydroxybenzaldehyde, syringaldehyde, and vanillin) as inhibitors of growth and ethanol production by ethanologenic derivatives of Escherichia coli B (strains K011 and LY01). Aromatic aldyhydes were at least twice as toxic as furfural of 5-hydroxymethylfurfural on a weight basis. The toxicities of all aldehydes (and ethanol) except furfural were additive when tested in binary combinations. In all cases, combinations with furfural were unexpectedly toxic. Although the potency of these aldehydes was directly related to hydrophobicity indicating a hydrophobic site of action, none caused sufficient membrane damage to allow the leakage of intracellular magnesium even when present at sixfold the concentrations required for growth inhibition. Of the aldehydes tested, only furfural strongly inhibited ethanol production in vitro. A comparison with published results for other microorganisms indicates that LY01 is equivalent or more resistant than other biocatalysts to the aldehydes examined in this study.

  7. Effect of endogenous carotenoids on “adaptive” mutation in Escherichia coli FC40

    Science.gov (United States)

    Bridges, Bryn A.; Foster, Patricia L.; Timms, Andrew R.

    2010-01-01

    The appearance over many days of Lac+ frameshift mutations in Escherichia coli strain FC40 incubated on lactose selection plates is a classic example of apparent “adaptive” mutation in an episomal gene. We show that endogenously overproduced carotenoids reduce adaptive mutation under selective conditions by a factor of around two. Carotenoids are known to scavenge singlet oxygen suggesting that the accumulation of oxidative base damage may be an integral part of the adaptive mutation phenomenon. If so, the lesion cannot be 7,8-dihydro-8-oxoguanine since adaptive mutation in FC40 is unaffected by mutM and mutY mutations. If active oxygen species such as singlet oxygen are involved in adaptive mutation then they should also induce frameshift mutations in FC40 under non-selective conditions. We show that such mutations can be induced under non-selective conditions by protoporphyrin photosensitisation and that this photodynamic induction is reduced by a factor of just over two when endogenous carotenoids are present. We argue that the involvement of oxidative damage would in no way be inconsistent with current understanding of the mechanism of adaptive mutation and the role of DNA polymerases. PMID:11166030

  8. Differential effects of procaine and phenethyl alcohol on excision repair of DNA in u.v.-irradiated Escherichia coli

    International Nuclear Information System (INIS)

    Tomiyama, H.; Tachibana, A.; Yonei, S.

    1986-01-01

    Experiments were performed to investigate the involvement of the cell membrane in the excision DNA repair process in Escherichia coli. Two membrane-binding drugs, procaine and phenethyl alcohol (PEA), inhibited liquid-holding recovery (LBR) in u.v.-irradiated E. coli wild-type and recA strains. In uvrB and polA strains where, after u.v.-irradiation, LHR was absent the two drugs had no effect. Both drugs markedly reduced the removal of u.v.-induced thymine dimers in the DNA of wild-type cells (H/r30). Analysis by alkaline sucrose gradients revealed that PEA inhibited the incision step in excision repair. In contrast, procaine had no effect on incision but apparently inhibited the late steps in excision repair. PEA dissociated DNA from the cell membrane, whereas procaine did not. The results suggest that the two drugs PEA and procaine inhibit LHR and the excision repair process operating on u.v.-induced damage in E. coli by at least two different mechanisms each of which may involve the cell membrane. (author)

  9. Effects of hot water application after defeathering on the levels of Campylobacter, coliform bacteria, and Escherichia coli on broiler carcasses.

    Science.gov (United States)

    Berrang, M E; Dickens, J A; Musgrove, M T

    2000-11-01

    Scalding has been found to lower the levels of Campylobacter on broiler carcasses. However, the numbers recovered from whole-carcass rinse samples increase following defeathering. This study was undertaken to examine the effect of a second scald applied after defeathering on microbial levels recovered from carcass rinses. Four treatments were evaluated: 1) immersion at 60 C for 28 s 30 min after defeathering, 2) immersion at 60 C for 28 s immediately after defeathering, 3) spray at 73 C for 20 s 30 min after defeathering, and 4) spray at 71 C for 20 s immediately after defeathering. As reported earlier, a significant increase in Campylobacter counts per mL whole carcass rinse was noted after carcasses were defeathered. However, when applied 30 min after defeathering, neither the immersion nor the spray second scald treatments lowered the Campylobacter counts. Likewise, neither treatment had any affect on Escherichia coli or coliform bacteria counts, even though total counts were slightly reduced by the treatments. When the second scald treatment immediately followed defeathering, the same trends were observed. Campylobacter counts after the second scald remained at the postpick levels, as did counts for E. coli and coliform bacteria, but total plate counts were slightly reduced. Overall, it would appear that a postscald treatment gentle enough not to alter the carcass appearance or meat quality would not effectively lower Campylobacter, E. coli, or coliform bacteria counts.

  10. Investigation of lethal and mutagenetic effects of UV-light on Salmonella currying wild and mutant alleles of lex A gene of Escherichia coli in the Salmonella genome

    International Nuclear Information System (INIS)

    Andreeva, I.V.; Tiganova, I.G.; Skavronskaya, A.G.

    1981-01-01

    Inheritance of LexA-gene of Escherichia coli- by Salmonella takes place during intergeneric trunsduction cross of Escherichia coli and Salmonella typhimurium. The presence of LexA-E. coli gene-did not eliminate earlier revealed peculiarity consisting in the absence of UV-induced mutagenesis in most of studied salmonollosis strains. So it is shown that the absence of UV mutagenesis in Salmonella does not result from mutation in LexA-gene. Inheritance of pKM101 by LexA-hybrid provides pronounced UV mutability and protective effect. Inheritance of this plasmid by LexA-hybrid did not result in the appearance of capability for UV-induced mutagenesis and improving UV resistance of bacteria. Thus the plasmids effect on repair and mutagenesis in Salmonella, the same as in E. coli, reveals in LexA-phenotype [ru

  11. Cefotaxime resistant Escherichia coli collected from a healthy volunteer; characterisation and the effect of plasmid loss.

    Directory of Open Access Journals (Sweden)

    Miranda Kirchner

    Full Text Available In this study 6 CTX-M positive E. coli isolates collected during a clinical study examining the effect of antibiotic use in a human trial were analysed. The aim of the study was to analyse these isolates and assess the effect of full or partial loss of plasmid genes on bacterial fitness and pathogenicity. A DNA array was utilised to assess resistance and virulence gene carriage. Plasmids were characterised by PCR-based replicon typing and addiction system multiplex PCR. A phenotypic array and insect virulence model were utilised to assess the effect of plasmid-loss in E. coli of a large multi-resistance plasmid. All six E. coli carrying bla CTX-M-14 were detected from a single participant and were identical by pulse field gel electrophoresis and MLST. Plasmid profiling and arrays indicated absence of a large multi-drug resistance (MDR F-replicon plasmid carrying blaTEM, aadA4, strA, strB, dfrA17/19, sul1, and tetB from one isolate. Although this isolate partially retained the plasmid it showed altered fitness characteristics e.g. inability to respire in presence of antiseptics, similar to a plasmid-cured strain. However, unlike the plasmid-cured or plasmid harbouring strains, the survival rate for Galleria mellonella infected by the former strain was approximately 5-times lower, indicating other possible changes accompanying partial plasmid loss. In conclusion, our results demonstrated that an apparently healthy individual can harbour bla CTX-M-14 E. coli strains. In one such strain, isolated from the same individual, partial absence of a large MDR plasmid resulted in altered fitness and virulence characteristics, which may have implications in the ability of this strain to infect and any subsequent treatment.

  12. Reuse of dredged marine soils as landfill liner: Effect of pH on Escherichia coli growth

    Science.gov (United States)

    Anuar, N. M.; Chan, C. M.

    2017-11-01

    A potential reuse area yet to be explored is the utilization of dredged marine soils (DMS) as geosorbent to retain pathogenic bacteria in landfill leachate. The use of DMS as geosorbent in landfill site could be considered as a new way of environmental friendly solid waste management. By laying DMS at the base of landfill like conventional clay liners, the geowaste could be simultaneously disposed of and act as passive geosorbent for microbes in leachate. DMS are known to serve as a hospitable environment for bacteria growth. Environmental factors such as soil’s pH, salinity and particle size could affect the bacteria growth rate. This study investigated the effect range of pH value on the growth of indicator bacteria, Escherichia coli (E. coli) isolated from landfill leachate. The results showed that the number of E. coli grew higher in alkaline compared to acidic condition. Findings from this study will serve as a base for future studies for removing bacteria in leachate using DMS as geosorbent in a landfill site.

  13. Bactericidal effect of bovine lactoferrin, LFcin, LFampin and LFchimera on antibiotic-resistant Staphylococcus aureus and Escherichia coli.

    Science.gov (United States)

    Flores-Villaseñor, Héctor; Canizalez-Román, Adrian; Reyes-Lopez, Magda; Nazmi, Kamram; de la Garza, Mireya; Zazueta-Beltrán, Jorge; León-Sicairos, Nidia; Bolscher, Jan G M

    2010-06-01

    Increased prevalence of antibiotic-resistant bacteria has become a major threat to the health sector worldwide due to their virulence, limited therapeutic options and distribution in both hospital and community settings. Discovery and development of new agents to combat antibiotic-resistant bacteria is thus needed. This study therefore aimed to evaluate the ability of bovine lactoferrin (LF), peptides from two antimicrobial domains lactoferricin B (LFcin17-30) and lactoferrampin (LFampin265-284) and a chimeric construct (LFchimera) containing both peptides, as potential bactericidal agents against clinical isolates of antibiotic-resistant Staphylococcus aureus and Escherichia coli. Results in kinetics of growth show that LF chimera and peptides inhibited the growth of both bacterial species. By confocal microscopy and flow cytometry it was observed that LF and FITC-labeled peptides are able to interact with these bacteria and cause membrane permeabilization, as monitored by propidium iodide staining, these effects were decreased by preincubation with lipopolysaccharide in E. coli. By electron microscopy, a clear cellular damage was observed in bacteria after treatments with LFchimera and peptides, suggesting that interaction and membrane disruption are probably involved as a mechanism of action. In conclusion, results show that LFchimera, LF and peptides have potential as bactericidal agents in the antibiotic-resistant strains of S. aureus and E. coli and also the work strongly suggest that LFcin17-30 and LFampin265-284 acts synergistically with antibiotics against multidrug resistant EPEC and MRSA in vitro.

  14. Antimicrobial resistance of Escherichia coli isolated in newly-hatched chickens and effect of amoxicillin treatment during their growth.

    Science.gov (United States)

    Jiménez-Belenguer, Ana; Doménech, Eva; Villagrá, Arantxa; Fenollar, Alejandro; Ferrús, Maria Antonia

    2016-08-01

    The use of antimicrobials in food animals is the major determinant for the propagation of resistant bacteria in the animal reservoir. However, other factors may also play a part, and in particular vertical spread between the generations has been suggested to be an important transmission pathway. The objective of this paper was to determine the resistance patterns of Escherichia coli isolated from newly-hatched chickens as well as to study the antibiotic pressure effect when amoxicillin was administered during their growing period. With this aim, meconium from 22 one-day-old Ross chickens was analysed. In addition, during their growth period, amoxicillin treatments at days 7, 21 and 35 were carried out. Results showed a high number of E. coli-resistant strains were isolated from the treated one-day-old chickens, and were the highest for β-lactams group, followed by quinolone and tetracyclines. After treatment with amoxicillin, the highest percentage of resistances were detected for this antibiotic compared to the others analysed, with significant differences in resistance percentages between control and treated broilers detected in relation to ampicillin, cephalothin, streptomycin, kanamycin, gentamicin, chloramphenicol and tetracycline. Differences in resistances to ciprofloxacin and nalidixic acid between control and treated animals were not observed and there was lack of resistance for amikacin and ceftriaxone. These results suggest the possibility of vertical transmission of resistant strains to newly-hatched chicks from parent flocks, and seem to indicate that the treatment with amoxicillin increased the resistance of E. coli to other antibiotics.

  15. Effect of x-ray treatments on Escherichia coli O157:H7, Listeria monocytogenes, Shigella flexneri, Salmonella enterica and inherent microbiota on whole mangoes

    Science.gov (United States)

    The aims of this investigation were to; (i) study the effect of X-ray treatments in reducing Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Shigella flexneri on whole mangoes, and (ii) study the effect of Xray treatments on microflora counts (mesophilic counts, psychrotrop...

  16. Effect of X-ray treatments on Escherichia coli 0157:H7, Listeria monocytogenes, Shigella flexneri, Salmonella enterica and inherent microbiota on whole mangoes

    Science.gov (United States)

    The aims of this investigation were to; (i) study the effect of X-ray treatments in reducing Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Shigella flexneri on whole mangoes, and (ii) study the effect of Xray treatments on microflora counts (mesophilic counts, psychrotrop...

  17. Comparison of the effect of nalidixic acid and thymine deprivation on excision repair in Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Masek, F; Slezarikova, V; Sedliakova, M [Slovenska Akademia Vied, Bratislava (Czechoslovakia). Vyskumny Ustav Onkologicky

    1975-01-01

    A difference was found in the extent of inhibition of thymine dimers (TT) excision in ultraviolet (UV) irradiated cells of E. coli after preirradiation depression of protein and DNA syntheses induced by a simultaneous removal of essential amino acids (AA/sup -/) and thymine (T/sup -/) or by the removal of essential amino acids and the addition of nalidixic acid (NAL/sup +/). The difference was observed in both E. coli B/r Hcr/sup +/ and E. coli K12 SR20 uvr/sup +/ cells. The depression of DNA synthesis by nalidixic acid as an exogenous agent inhibited TT excision to a lower degree than the depression of DNA synthesis by thymine starvation. The extent of TT excision had no appreciable effect on the restoration of the sedimentation profile of a newly synthesized DNA nor on UV resistance of cells during dark repair. A DNA molecule having the size of a molecule of nonirradiated cells became synthesized while TT were still present in the DNA.

  18. 77 FR 9888 - Shiga Toxin-Producing Escherichia coli

    Science.gov (United States)

    2012-02-21

    ... Toxin-Producing Escherichia coli in Certain Raw Beef Products AGENCY: Food Safety and Inspection Service... toxin-producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145). This new date..., that are contaminated with Shiga toxin-producing Escherichia coli (STEC) O26, O45, O103, O111, O121...

  19. Infectious endocarditis caused by Escherichia coli

    DEFF Research Database (Denmark)

    Lauridsen, Trine Kiilerich; Arpi, Magnus; Fritz-Hansen, Thomas

    2011-01-01

    Although Escherichia coli is among the most common causes of Gram-negative bacteraemia, infectious endocarditis (IE) due to this pathogen is rare. A 67-y-old male without a previous medical history presented with a new mitral regurgitation murmur and persisting E. coli bacteraemia in spite of broad......-spectrum intravenous antibiotics. Transthoracic and transoesophageal echocardiography revealed a severe mitral endocarditis. E. coli DNA was identified from the mitral valve and the vegetation, and no other pathogen was found. The case was further complicated by spondylodiscitis and bilateral endophthalmitis. Extra...

  20. Initiation of Replication in Escherichia coli

    DEFF Research Database (Denmark)

    Frimodt-Møller, Jakob

    The circular chromosome of Escherichia coli is replicated by two replisomes assembled at the unique origin and moving in the opposite direction until they meet in the less well defined terminus. The key protein in initiation of replication, DnaA, facilitates the unwinding of double-stranded DNA...... to single-stranded DNA in oriC. Although DnaA is able to bind both ADP and ATP, DnaA is only active in initiation when bound to ATP. Although initiation of replication, and the regulation of this, is thoroughly investigated it is still not fully understood. The overall aim of the thesis was to investigate...... the regulation of initiation, the effect on the cell when regulation fails, and if regulation was interlinked to chromosomal organization. This thesis uncovers that there exists a subtle balance between chromosome replication and reactive oxygen species (ROS) inflicted DNA damage. Thus, failure in regulation...

  1. Effect of several food ingredients on radiation inactivation of Escherichia coli and Listeria monocytogenes inoculated into ground pork

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Hyejeong [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Lacroix, Monique [Canadian Irradiation Center, Research Laboratory in Science Applied to Food, INRS-Institut Armand-Frappier, Qebec (Canada); Jung, Samooel [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kim, Keehyuk [Department of Culinary Nutrition, Woosong University, Daejeon 300-718 (Korea, Republic of); Lee, Ju Woon [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Jo, Cheorun, E-mail: cheorun@cnu.ac.kr [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2011-09-15

    The objective of this study was to examine the effects of several food ingredients on the relative radiation sensitivity (RRS) of Escherichia coli and Listeria monocytogenes inoculated onto ground pork. Garlic, leek, onion, and ginger were prepared in 3 different forms; pressurized, freeze-dried, and 70% ethanol extracted. The prepared food ingredients were subdivided into 2 groups, non-irradiated and irradiated with 5 kGy of gamma irradiation, before addition to ground pork. The prepared food ingredients were added at concentrations of 1% and 5% (w/w) into radiation-sterilized ground pork and inoculated with E. coli and L. monocytogenes (10{sup 6} CFU/mL). For E. coli inoculated pork, the most efficient ingredient was ethanol extracted leek (RRS=3.89), followed by freeze-dried ginger and leek (RRS=3.66 and 3.63, respectively) when used without pasteurization. However, when the food ingredients were irradiation-pasteurized, the freeze-dried ginger showed the highest RRS (4.10). When 5% natural materials were added, RRS was the highest for freeze-dried and ethanol extracted onion (4.44 and 4.65, respectively). For L. monocytogenes, the RRS was relatively lower than E. coli in general. The most efficient material was pressurized and freeze-dried onion (RRS=2.13 and 2.08, respectively) at a concentration of 1%. No increase in RRS was observed at increased concentration of food ingredients. These results suggest that the addition of particular food ingredients increased the efficiency of radiation-sterilization. However, changes in RRS were dependent on the species of microorganism as well as the form of the food ingredients. - Highlights: > Several food ingredients increased the efficiency of irradiation sterilization. > Different forms of food ingredients may affect the efficiency. > The increase of efficiency decreased the required irradiation dose, thereby avoiding sensory impairments of food.

  2. Effect of several food ingredients on radiation inactivation of Escherichia coli and Listeria monocytogenes inoculated into ground pork

    International Nuclear Information System (INIS)

    Yun, Hyejeong; Lacroix, Monique; Jung, Samooel; Kim, Keehyuk; Lee, Ju Woon; Jo, Cheorun

    2011-01-01

    The objective of this study was to examine the effects of several food ingredients on the relative radiation sensitivity (RRS) of Escherichia coli and Listeria monocytogenes inoculated onto ground pork. Garlic, leek, onion, and ginger were prepared in 3 different forms; pressurized, freeze-dried, and 70% ethanol extracted. The prepared food ingredients were subdivided into 2 groups, non-irradiated and irradiated with 5 kGy of gamma irradiation, before addition to ground pork. The prepared food ingredients were added at concentrations of 1% and 5% (w/w) into radiation-sterilized ground pork and inoculated with E. coli and L. monocytogenes (10 6 CFU/mL). For E. coli inoculated pork, the most efficient ingredient was ethanol extracted leek (RRS=3.89), followed by freeze-dried ginger and leek (RRS=3.66 and 3.63, respectively) when used without pasteurization. However, when the food ingredients were irradiation-pasteurized, the freeze-dried ginger showed the highest RRS (4.10). When 5% natural materials were added, RRS was the highest for freeze-dried and ethanol extracted onion (4.44 and 4.65, respectively). For L. monocytogenes, the RRS was relatively lower than E. coli in general. The most efficient material was pressurized and freeze-dried onion (RRS=2.13 and 2.08, respectively) at a concentration of 1%. No increase in RRS was observed at increased concentration of food ingredients. These results suggest that the addition of particular food ingredients increased the efficiency of radiation-sterilization. However, changes in RRS were dependent on the species of microorganism as well as the form of the food ingredients. - Highlights: → Several food ingredients increased the efficiency of irradiation sterilization. → Different forms of food ingredients may affect the efficiency. → The increase of efficiency decreased the required irradiation dose, thereby avoiding sensory impairments of food.

  3. Anti-bacterial effect of essential oil from Xanthium strumarium against shiga toxin-producing Escherichia coli.

    Science.gov (United States)

    Sharifi-Rad, J; Soufi, L; Ayatollahi, S A M; Iriti, M; Sharifi-Rad, M; Varoni, E M; Shahri, F; Esposito, S; Kuhestani, K; Sharifi-Rad, M

    2016-09-19

    Shiga toxin-producing Escherichia coli (STEC) serotype O157:H7 is one of the most important human pathogenic microorganisms, which can cause life-threatening infections. Xanthium strumarium L. is a plant with anti-bacterial activity against gram-negative and gram-positive bacteria. This study aims to demonstrate in vitro efficacy of the essential oil (EO) extracted from Xanthium strumarium L. against E. coli O157:H7. Using the agar test diffusion, the effect of Xanthium strumarium L. EO (5, 10, 15, 30, 60, and 120 mg/mL) was verified at each of the four different growth phases of E. coli O157:H7. Cell counts of viable cells and colony forming unit (CFU) were determined at regular time points using Breed's method and colony counting method, respectively. No viable cell was detectable after the 1 hour-exposure to X. strumarium EO at 30, 60, and 120 mg/mL concentrations. No bacterial colony was formed after 1 h until the end of the incubation period at 24 h. At lower concentrations, the number of bacteria cells decreased and colonies could be observed only after incubation. At the exponential phase, the EO at 15 mg/mL was only bacteriostatic, while from 30 mg/mL started to be bactericidal. X. strumarium EO antibacterial activity against Shiga toxin-producing E. coli O157:H7 is dependent on EO concentration and physiological state of the microorganisms tested. The best inhibitory activity was achieved during the late exponential and the stationary phases.

  4. Effect of several food ingredients on radiation inactivation of Escherichia coli and Listeria monocytogenes inoculated into ground pork

    Science.gov (United States)

    Yun, Hyejeong; Lacroix, Monique; Jung, Samooel; Kim, Keehyuk; Lee, Ju Woon; Jo, Cheorun

    2011-09-01

    The objective of this study was to examine the effects of several food ingredients on the relative radiation sensitivity (RRS) of Escherichia coli and Listeria monocytogenes inoculated onto ground pork. Garlic, leek, onion, and ginger were prepared in 3 different forms; pressurized, freeze-dried, and 70% ethanol extracted. The prepared food ingredients were subdivided into 2 groups, non-irradiated and irradiated with 5 kGy of gamma irradiation, before addition to ground pork. The prepared food ingredients were added at concentrations of 1% and 5% (w/w) into radiation-sterilized ground pork and inoculated with E. coli and L. monocytogenes (10 6 CFU/mL). For E. coli inoculated pork, the most efficient ingredient was ethanol extracted leek (RRS=3.89), followed by freeze-dried ginger and leek (RRS=3.66 and 3.63, respectively) when used without pasteurization. However, when the food ingredients were irradiation-pasteurized, the freeze-dried ginger showed the highest RRS (4.10). When 5% natural materials were added, RRS was the highest for freeze-dried and ethanol extracted onion (4.44 and 4.65, respectively). For L. monocytogenes, the RRS was relatively lower than E. coli in general. The most efficient material was pressurized and freeze-dried onion (RRS=2.13 and 2.08, respectively) at a concentration of 1%. No increase in RRS was observed at increased concentration of food ingredients. These results suggest that the addition of particular food ingredients increased the efficiency of radiation-sterilization. However, changes in RRS were dependent on the species of microorganism as well as the form of the food ingredients.

  5. Optimization of plasmid electrotransformation into Escherichia coli ...

    African Journals Online (AJOL)

    In order to improve electroporation, optical density of bacteria, recovery time and electrical parameter (field strength and capacitance) were optimized using the Taguchi statistical method. ANOVA of obtained data indicated that the optimal conditions of electrotransformation of pET-28a (+) plasmid into Escherichia coli ...

  6. (ESBL) producing Escherichia coli and Klebsiella pneumoniae

    African Journals Online (AJOL)

    Emerging antibiotic resistance due to extended spectrum β-lactamase (ESBL) production limited the use of β-lactam antibiotics against Escherichia coli and Klebsiella pneumoniae. This observational study was conducted at the Microbiology department of the Children's Hospital, Lahore Pakistan, from June, 2009 to ...

  7. Mutagenic DNA repair in Escherichia coli

    International Nuclear Information System (INIS)

    Bridges, B.A.; Sharif, Firdaus

    1986-01-01

    The authors report a study of the misincorporation step in excision proficient umuC Escherichia coli as revealed by delayed photoreversal and show that it parallels the loss of photoreversibility of mutations induced in isogenic umu + bacteria; in both cases the end-point was mutation to streptomycin resistance. (author)

  8. Antibiotic resistance properties of uropathogenic Escherichia coli ...

    African Journals Online (AJOL)

    Purpose: To investigate the antibiotic resistance pattern of uropathogenic Escherichia coli (UPEC) strains isolated from pregnant women with history of recurrent urinary tract infections (RUTIs) and healthy pregnant women. Methods: A total of 485 high vaginal swab specimens were collected from pregnant women with ...

  9. Prevalence of Arcobacter, Escherichia coli, Staphylococcus aureus ...

    African Journals Online (AJOL)

    In this study, varying level of resistance of Escherichia coli 66(84.6%), Salmonella 6(100%) and Arcobacter 57(100%) to amoxicillin was observed. The susceptibility pattern indicates that the bacterial isolates exhibited a varying level of resistance to two or more antimicrobial agents with maximum resistance to amoxicillin.

  10. Leaner and meaner genomes in Escherichia coli

    DEFF Research Database (Denmark)

    Ussery, David

    2006-01-01

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

  11. ANTIMICIROBIAL SUSCEPTIBILITY PATTERNS OF Escherichia coli ...

    African Journals Online (AJOL)

    DR. AMINU

    A total of 56 and 24 strains of E. coli and Shigella sp. isolated from children less than five years with diarrhoea attending 3 ... parasitic infections, as well as food intolerance, reaction to ..... Escherichia coil 0157:H7 as a model of entry of a new.

  12. Effect of storage temperature on survival and recovery of thermal and extrusion injured Escherichia coli populations in whey protein concentrate and corn meal

    Science.gov (United States)

    In a previous study, we reported viability loss of Escherichia coli populations in corn (CP) and whey protein products (WPP) extruded at different temperatures. However, information on the effect of storage temperatures on injured bacterial populations was not addressed. The objective of this study ...

  13. The effect of deep frying or conventional oven cooking on inactivation of Shiga toxin-producing cells of Escherichia coli (STEC) in meatballs

    Science.gov (United States)

    We investigated the effects deep frying or oven cooking on inactivation of Shiga toxin-producing cells of Escherichia coli (STEC) in meatballs. A finely-ground veal and/or a beef-pork-veal mixture were inoculated (ca. 7.0 log CFU/g) with an eight-strain, genetically-marked cocktail of rifampicin-res...

  14. Modeling the contamination of lettuce with Escherichia coli 157:H7 from manure-amended soil and the effect of intervention strategies

    NARCIS (Netherlands)

    Franz, E.; Semenov, A.V.; Bruggen, van A.H.C.

    2008-01-01

    Aims: A growing number of foodborne illnesses has been associated with the consumption of fresh produce. In this study, the probability of lettuce contamination with Escherichia coli O157:H7 from manure-amended soil and the effect of intervention strategies was determined. Methods and Results:

  15. Effect of high pressure impact on the survival of Shiga Toxin-producing Escherichia coli ('Big Six' and 0157) in ground beef

    Science.gov (United States)

    High pressure processing (HPP) is a safe and effective technology for improving food safety while maintaining food quality attributes. Non-O157:H7 Shiga Toxin-producing Escherichia coli (STEC) have been increasingly implicated in foodborne illness outbreaks and recalls, and the USDA Food Safety Ins...

  16. Effect of the mutation of recB21 of Escherichia coli on indirect recombinogenesis of bacteriophage lambda

    International Nuclear Information System (INIS)

    Castillo-Villanueva, A.

    1993-01-01

    In this work two undamaged amber lambda mutants were crossed in UV-irradiated Escherichia coli host cells and the total and recombinant λ + progenies scored after one lytic cycle. In a wild - type strain, such treatment produces an stimulation of 5-7 times in the production of recombinant λ + particles, accompanied by a variable but consistent increase in the total phage pro genie too. The effect has been designed as indirect recombinogenesis of bacteriophage lambda because it is elicited among undamaged λ genomes by the UV irradiation of host cells. Through the use of recB21 mutants we tested the role of the RecBCD enzyme as a whole in the effect just described and observed that in those hosts the effect is absent. The RecBCD enzyme of Escherichia coli has different activities, important for both the genetic recombination and recovery from DNA damage. Among those activities is that of ATP-dependent double-stranded DNA exonuclease, by means of which the enzyme digests the lineal molecules of viral DNA, produced during the late phase of lambda lytic cycle. To face such a destructive activity, λ encodes the Gam protein which inhibits all the activities of RecBCD; so the ability of RecBCD to act in the phage response, may be due either to a residual activity of the enzyme in lambda infected host cells or to an unknown Gam non-inhibited activity of the RecBCD enzyme. because the synthesis of the RecBCD is constitutive, the apparent inducibility of the λ response should be due to another reason such as an increase in the molecular substrates on which the enzyme acts. (Author)

  17. High-level expression of Bacillus naganoensis pullulanase from recombinant Escherichia coli with auto-induction: effect of lac operator.

    Directory of Open Access Journals (Sweden)

    Yao Nie

    Full Text Available Pullulanase plays an important role in specific hydrolysis of branch points in amylopectin and is generally employed as an important enzyme in starch-processing industry. So far, however, the production level of pullulanase is still somewhat low from wide-type strains and even heterologous expression systems. Here the gene encoding Bacillus naganoensis pullulanase was amplified and cloned. For expression of the protein, two recombinant systems, Escherichia coli BL21(DE3/pET-20b(+-pul and E. coli BL21(DE3/pET-22b(+-pul, were constructed, both bearing T7 promoter and signal peptide sequence, but different in the existance of lac operator and lacI gene encoding lac repressor. Recombinant pullulanase was initially expressed with the activity of up to 14 U/mL by E. coli BL21(DE3/pET-20b(+-pul with IPTG induction in LB medium, but its expression level reduced continually with the extension of cryopreservation time and basal expression was observed. However, E. coli BL21(DE3/pET-22b(+-pul , involving lac operator downstream of T7 promoter to regulate foreign gene transcription, exhibited pullulanase activity consistently without detected basal expression. By investigating the effect of lac operator, basal expression of foreign protein was found to cause expression instability and negative effect on production of target protein. Thus double-repression strategy was proposed that lac operators in both chromosome and plasmid were bound with lac repressor to repress T7 RNA polymerase synthesis and target protein expression before induction. Consequently, the total activity of pullulanase was remarkably increased to 580 U/mL with auto-induction by lac operator-involved E. coli BL21(DE3/pET-22b(+-pul. When adding 0.6% glycine in culture, the extracellular production of pullulanase was significantly improved with the extracellular activity of 502 U/mL, which is a relatively higher level achieved to date for extracellular production of pullulanase. The

  18. Effects of mutation on the downfield proton nuclear magnetic resonance spectrum of the 5S RNA of Escherichia coli

    International Nuclear Information System (INIS)

    Gewirth, D.T.; Moore, P.B.

    1987-01-01

    The imino proton spectra of several mutants of the 5S RNA of Escherichia coli are compared with that of the wild type. Three of the variants discussed are point mutations, and the fourth is a deletion mutant lacking bases 11-69 of the parent sequence, all obtained by site-directed mutagenesis techniques. The spectroscopic effects of mutation are limited in all cases, and the differences between normal and mutant spectra can be used to make or confirm the assignments of resonances. Several new assignments in the 5S spectrum are reported. Spectroscopic differences due to sequence differences permit the products of single genes within the 5S gene family to be distinguished and their fates followed by NMR

  19. The Escherichia coli modE gene: effect of modE mutations on molybdate dependent modA expression.

    Science.gov (United States)

    McNicholas, P M; Chiang, R C; Gunsalus, R P

    1996-11-15

    The Escherichia coli modABCD operon, which encodes a high-affinity molybdate uptake system, is transcriptionally regulated in response to molybdate availability by ModE. Here we describe a highly effective enrichment protocol, applicable to any gene with a repressor role, and establish its application in the isolation of transposon mutations in modE. In addition we show that disruption of the ModE C-terminus abolishes derepression in the absence of molybdate, implying this region of ModE controls the repressor activity. Finally, a mutational analysis of a proposed molybdate binding motif indicates that this motif does not function in regulating the repressor activity of ModE.

  20. Systematic replacement of lysine with glutamine and alanine in Escherichia coli malate synthase G: effect on crystallization

    International Nuclear Information System (INIS)

    Anstrom, David M.; Colip, Leslie; Moshofsky, Brian; Hatcher, Eric; Remington, S. James

    2005-01-01

    Alanine and glutamine mutations were made to the same 15 lysine positions on the surface of E. coli malate synthase G and the impact on crystallization observed. The results support lysine replacement for improvement of crystallization and provide insight into site selection and type of amino-acid replacement. Two proposals recommend substitution of surface lysine residues as a means to improve the quality of protein crystals. In proposal I, substitution of lysine by alanine has been suggested to improve crystallization by reducing the entropic cost of ordering flexible side chains at crystal contacts. In proposal II, substitution of lysine by residues more commonly found in crystal contacts, such as glutamine, has been proposed to improve crystallization. 15 lysine residues on the surface of Escherichia coli malate synthase G, distributed over a variety of secondary structures, were individually mutated to both alanine and glutamine. For 28 variants, detailed studies of the effect on enzymatic activity and crystallization were conducted. This has permitted direct comparison of the relative effects of the two types of mutations. While none of the variants produced crystals suitable for X-ray structural determination, small crystals were obtained in a wide variety of conditions, in support of the general approach. Glutamine substitutions were found to be more effective than alanine in producing crystals, in support of proposal II. Secondary structure at the site of mutation does not appear to play a major role in determining the rate of success

  1. Photoinactivation effect of eosin methylene blue and chlorophyllin sodium-copper against Staphylococcus aureus and Escherichia coli.

    Science.gov (United States)

    Caires, Cynthia S A; Leal, Cassia R B; Ramos, Carlos A N; Bogo, Danielle; Lima, Alessandra R; Arruda, Eduardo J; Oliveira, Samuel L; Caires, Anderson R L; Nascimento, Valter A

    2017-07-01

    The use of eosin methylene blue according to Giemsa as photosensitizer is presented for the first time in this paper. The present study evaluated the potential application of chlorophyllin sodium copper salt (CuChlNa) and eosin methylene blue according to Giemsa (EMB) as antimicrobial photosensitizers (aPS) for photodynamic inactivation (PDI) of Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria. The experiments were performed using S. aureus stain ATCC 25923 and E. coli ATCC 25922 in which five aPS concentrations (0.0, 1.0, 2.5, 5.0, 10.0, and 20.0 μM for S. aureus and 0.0, 5.0, 10.0, 20.0, 40.0, and 50.0 μM for E. coli) were prepared and added in 2 mL of a saline solution containing the bacterial inoculum. After aPS incubation, the samples were divided into two groups, one kept in the dark and another submitted to the illumination. Then, the bacterial inactivation was determined 18 h after the incubation at 37 °C by counting the colony-forming units (CFU). The results revealed that both EMB and CuChlNa can be used as aPS for the photoinactivation of S. aureus, while only EMB was able to photoinactivate E. coli. Nevertheless, a more complex experimental setup was needed for photoinactivation of E. coli. The data showed that EMB and CuChlNa presented similar photoinactivation effects on S. aureus, in which bacterial growth was completely inhibited at photosensitizer (PS) concentrations over 5 μM, when samples were previously incubated for 30 min and irradiated by a light dose of 30 J cm -2 as a result of an illumination of 1 h at 8.3 mW cm -2 by using a red light at 625 nm with a 1 cm beam diameter and output power of 6.5 mW. In the case of E. coli, bacterial growth was completely inhibited only when combining a PS incubation period of 120 min with concentrations over 20 μM.

  2. Thermal degradation products of saccharides: effect study over Escherichia coli K12S cells

    International Nuclear Information System (INIS)

    Oliveira, R.L.B.C. de.

    1980-01-01

    The heat sterilization of reducing sugars, in the presence of phosphates, in alkaline pH, promotes caramelization reactions, yielding a serie of degradation products. Among them, aldehyde-like compounds seem to be responsible for the decrease in viability of DNA repair-proficient E.coli cells. A positive interaction between toxic solutions and UV-radiation effects is observed in these cells. The sinergism UV-toxic solutions varies in function of post-irradiation time and is dependent on UV dose, indicating the interference of repair processes in toxicity. The effect of non-reducing sugars on cellular viability is negligible, suggesting that toxic substances generation is linked to the presence of at least a free carbonyl group in sugar structure. All tested reducing sugars, when experimental conditions remained constant, have similarly shaped inactivation kinetics and their effects are equally inhibited by catalase activity, during incubation. (author)

  3. Effects of beta-lactamases and omp mutation on susceptibility to beta-lactam antibiotics in Escherichia coli.

    Science.gov (United States)

    Hiraoka, M; Okamoto, R; Inoue, M; Mitsuhashi, S

    1989-01-01

    Four types of beta-lactamases consisting of a penicillinase type I (TEM-1), a penicillinase type II (OXA-1), a cephalosporinase of Citrobacter freundii, and a cephalosporinase of Proteus vulgaris were introduced into Escherichia coli MC4100 and its omp mutants, MH1160 (MC4100 ompR1) and MH760 (MC4100 ompR2), by transformation. Effects of the combination of the omp mutations and these beta-lactamases on the susceptibility of E. coli strains were studied with 15 beta-lactam antibiotics including cephalosporins, cephamycins, penicillins, imipenem, and aztreonam. The ompR1 mutant, MH1160, lacks OmpF and OmpC, and it showed reduced susceptibility to 11 of the 15 beta-lactam agents. The reduction in susceptibility to cefoxitin, moxalactam, and flomoxef was much greater than reduction in susceptibility to the other agents. When the ompR1 mutant produced the cephalosporinase of C. freundii, the susceptibility of the mutant to 12 of the 15 beta-lactam antibiotics decreased. The reduction in susceptibility of MH1160 to 10 of the 12 agents affected by the enzyme was two- to fourfold greater than that observed in MC4100. Such a synergistic effect was also observed with the cephalosporinase of P. vulgaris and ompR1 mutation against six cephalosporins, moxalactam, and aztreonam. Images PMID:2658786

  4. Prebiotic effect of Jerusalem artichoke (Helianthus tuberosus fructans on the growth performance of Bifiobacterium bifium and Escherichia coli

    Directory of Open Access Journals (Sweden)

    Mansouri elaheh

    2016-05-01

    Full Text Available Objective: To investigate and compare in vitro prebiotic effects of Jerusalem artichoke polyfructans on the survivability and activity of Bifiobacterium bifium and Escherichia coli with high performance-inulin (a high molecular weight fraction of chicory-derived inulin. Methods: Extracted polyfructose from Jerusalem artichoke tubers and standard inulin were added to the appropriated culture to achieve final concentrations [0.5%, 1.0%, 2.0% and 3.0% (w/v] to determine the turbidity and pH variations during 48 h incubation. Results: This study suggested that Jerusalem artichoke tuber fructooligosaccharides had the potential to be used as a prebiotic component. The growth of Bifidobacterium bifidum improved significantly in the presence of Jerusalem artichoke fructans compared to the control. There was no significant differences (P < 0.05 in Bifidobacterium population in different concentrations of Jerusalem artichoke poly-fructans, but the population was significantly higher than the count in the presence of high performance-inulin. The pH decreased in both media during 48 h incubation time. The specific rate of growth and doubling time determined for Escherichia coli demonstrated that the efficacy of various carbon sources in stimulating bacterial growth was influenced by the concentration and degree of polymerization of fructan chains in the media. Conclusions: Jerusalem artichoke fructooligosaccharides can provide the greater stability of probiotics and acid production, so it can be considered as a potential source of high yielding oligosaccharide for commercial prebiotic production to develop food industry and improve host health.

  5. Rapid assessment of the effect of ciprofloxacin on chromosomal DNA from Escherichia coli using an in situ DNA fragmentation assay

    Directory of Open Access Journals (Sweden)

    Gosalvez Jaime

    2009-04-01

    Full Text Available Abstract Background Fluoroquinolones are extensively used antibiotics that induce DNA double-strand breaks (DSBs by trapping DNA gyrase and topoisomerase IV on DNA. This effect is usually evaluated using biochemical or molecular procedures, but these are not effective at the single-cell level. We assessed ciprofloxacin (CIP-induced chromosomal DNA breakage in single-cell Escherichia coli by direct visualization of the DNA fragments that diffused from the nucleoid obtained after bacterial lysis in an agarose microgel on a slide. Results Exposing the E. coli strain TG1 to CIP starting at a minimum inhibitory concentration (MIC of 0.012 μg/ml and at increasing doses for 40 min increased the DNA fragmentation progressively. DNA damage started to be detectable at the MIC dose. At a dose of 1 μg/ml of CIP, DNA damage was visualized clearly immediately after processing, and the DNA fragmentation increased progressively with the antibiotic incubation time. The level of DNA damage was much higher when the bacteria were taken from liquid LB broth than from solid LB agar. CIP treatment produced a progressively slower rate of DNA damage in bacteria in the stationary phase than in the exponentially growing phase. Removing the antibiotic after the 40 min incubation resulted in progressive DSB repair activity with time. The magnitude of DNA repair was inversely related to CIP dose and was noticeable after incubation with CIP at 0.1 μg/ml but scarce after 10 μg/ml. The repair activity was not strictly related to viability. Four E. coli strains with identified mechanisms of reduced sensitivity to CIP were assessed using this procedure and produced DNA fragmentation levels that were inversely related to MIC dose, except those with very high MIC dose. Conclusion This procedure for determining DNA fragmentation is a simple and rapid test for studying and evaluating the effect of quinolones.

  6. Effects of Bos taurus autosome 9-located quantitative trait loci haplotypes on enzymatic mastitis indicators of milk from dairy cows experimentally inoculated with Escherichia coli

    DEFF Research Database (Denmark)

    Sørensen, Lars Peter; Engberg, Ricarda Greuel; Løvendahl, Peter

    2015-01-01

    The aim of this study was to investigate the effect of a quantitative trait locus associated with mastitis caused by Escherichia coli, with one haplotype being more susceptible (HH) and another being more resistant (HL) to E. coli mastitis, on the activity of 4 inflammatory related milk enzymes....... In particular, we investigated the suitability of β-glucuronidase (GLU) as an early indicator of E. coli mastitis. Besides GLU, the enzymes l-lactate dehydrogenase (LDH), N-acetyl-β-d-glucosaminidase (NAGase), and alkaline phosphatase were included. The study was conducted in an experimental setup with 31...... Holstein cows divided into 4 groups representing repeated experiments and, within group, divided according to quantitative trait locus haplotype. All cows were inoculated with viable E. coli, and milk samples were collected 27 times from −6 to 396 h post-E. coli inoculation (PI). Activity of the 4 enzymes...

  7. Infektionen mit darmpathogenen Escherichia coli.

    NARCIS (Netherlands)

    Friedrich, Alexander; Stein, Jürgen; Dignass, Axel

    2001-01-01

    E. coli ist ein wesentlicher Bestandteil der physiologischen Darmflora des Menschen. Die üblicherweise im Darm vorkommenden Kolibakterien sind apathogen und für den Menschen eher nützlich (Sonnenborn u. Greinwald 1990). Allerdings kennen wir bei dieser Bakterienspezies auch ein breites Spektrum von

  8. The effect of a probiotic Escherichia coli strain on regulatory T-cells in six year-old children.

    Science.gov (United States)

    Hrdý, J; Kocourková, I; Lodinová-Žádníková, R; Kolářová, L; Prokešová, L

    2016-11-30

    Probiotics are believed to prevent or reduce allergy development but the mechanism of their beneficial effect is still poorly understood. Immune characteristics of regulatory T cells (Tregs) in peripheral blood of perinatally probiotic-supplemented children of allergic mothers (51 children), non-supplemented children of allergic mothers (42 children), and non-supplemented children of healthy mothers (28 children) were compared at the age of 6-7 years. A first dose of a probiotic Escherichia coli strain (E. coli O83:K24:H31) was administered within 2 days after the birth and then 12 times during the first months of life and children were followed longitudinally. Proportion and functional properties of Tregs were estimated by flow cytometry in relation to the children's allergy status. Proportion of Tregs in the peripheral blood of children suffering from allergy tends to be higher whereas median of fluorescence intensity (MFI) of FoxP3 was significantly decreased in allergic group. Intracellular presence of regulatory cytokine interleukin (IL)-10 was also lower in allergic children. Immune functions of Tregs reflected by both MFI of FoxP3 and IL-10 in the group of probiotic-supplemented children of allergic mothers were nearly comparable with children of healthy mothers while probiotic non-supplemented children of allergic mothers have decreased immune function of Tregs. Supplementation by probiotic E. coli strain decreases allergy incidence in high-risk children. In contrast to our expectation, proportion of Tregs has not been increased in probiotic supplemented children. Beneficial effect of probiotics on newborn immature immune system could be, at least partially, explained by the modulating immune function of Tregs. In summary, we detected increased proportion of Tregs in peripheral blood of allergic children, their functional properties were decreased in comparison with the Tregs of healthy children. A unifying hypothesis for these findings is that Treg numbers

  9. SOS gene induction and possible mutagenic effects of freeze-drying in Escherichia coli and Salmonella typhimurium.

    Science.gov (United States)

    Rosen, Rachel; Buchinger, Sebastian; Pfänder, Ramona; Pedhazur, Rami; Reifferscheid, Georg; Belkin, Shimshon

    2016-11-01

    We report the results of a study of the potential negative effects of the freeze-drying process, normally considered a benign means for long-term conservation of living cells and the golden standard in bacterial preservation. By monitoring gene induction using a whole-cell Escherichia coli bioreporter panel, in which diverse stress-responsive gene promoters are fused to luminescent or fluorescent reporting systems, we have demonstrated that DNA repair genes belonging to the SOS operon (recA, sulA, uvrA, umuD, and lexA) were induced upon resuscitation from the freeze-dried state, whereas other stress-responsive promoters such as grpE, katG, phoA, soxS, and sodA were not affected. This observation was confirmed by the UMU-chromotest (activation of the umuD gene promoter) in Salmonella typhimurium, as well as by real-time PCR analyses of selected E. coli SOS genes. We further show that a functional SOS operon is important in viability maintenance following resuscitation, but that at the same time, this repair system may introduce significantly higher mutation rates, comparable to those induced by high concentrations of a known mutagen. Our results also indicate that the entire freeze-drying process, rather than either freezing or drying separately, is instrumental in the induction of DNA damage.

  10. Effect of Lactobacillus rhamnosus on the response of Galleria mellonella against Staphylococcus aureus and Escherichia coli infections.

    Science.gov (United States)

    Jorjão, Adeline Lacerda; de Oliveira, Felipe Eduardo; Leão, Mariella Vieira Pereira; Jorge, Antonio Olavo Cardoso; de Oliveira, Luciane Dias

    2018-04-01

    This study evaluated the prophylactic effects of the live or heat-killed probiotic strain Lactobacillus rhamnosus ATCC 7469 in Galleria mellonella, inoculated with Staphylococcus aureus or Escherichia coli. L. rhamnosus suspension was prepared and a part of it was autoclaved to obtain heat-killed lactobacilli. The larvae were inoculated of these suspensions and pathogenic. The survival of the larvae was observed during 7 days and after 24 h of inoculation haemocytes counted, melanization and nitric oxide production were analyzed. Larvae survival rate increased in the group inoculated with heat-killed L. rhamnosus, however, with no statistical difference. There was a significant increase in total haemocyte counts in all test groups. Haemolymph melanization and nitric oxide production were higher in the group inoculated with L. rhamnosus and infected with S. aureus. It was concluded that, in this model of infection, heat-killed L. rhamnosus ATCC 7469 promoted greater protection in Galleria mellonella infected with S. aureus or E. coli.

  11. Indirect effects are involved in the production of potentially lethal damage in X irradiated escherichia coli

    International Nuclear Information System (INIS)

    Billen, D.

    1985-01-01

    When living cells are exposed to low LET radiation, 60 to 70% of the resulting lethality is said to be due to indirect effects. Using the OH radical scavengers: glycerol n-butanol, t-butanol, and NO/sub 2//sup -/. The authors observed that a radiosensitive E. coli K-12 mutant (W 3110 thy/sup -/ polAl/sup -/) lacking DNA polymerase 1 displays a markedly enhanced radioresistance when exposed to X rays in the presence of these chemicals. The extent of protection afforded by these chemicals correlated with their OH radical scavenging ability over the limited range of concentrations of the chemicals studied. (Only non-toxic concentrations of the chemicals were used). The presence of 2M glycerol during irradiation of the PolAl/sup -/ cells results in a survival level higher than that seen for the unprotected parent strain (W 3110 thy polA/sup +/)

  12. Evaluation of the Biological Effects of Externally Tunable, Hydrogel Encapsulated Quantum Dot Nanospheres in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Somesree GhoshMitra

    2011-08-01

    Full Text Available Quantum Dots (QDs have become an interesting subject of study for labeling and drug delivery in biomedical research due to their unique responses to external stimuli. In this paper, the biological effects of a novel hydrogel based QD nano-structure on E. coli bacteria are presented. The experimental evidence reveals that cadmium telluride (CdTe QDs that are encapsulated inside biocompatible polymeric shells have reduced or negligible toxicity to this model cell system, even when exposed at higher dosages. Furthermore, a preliminary gene expression study indicates that QD-hydrogel nanospheres do not inhibit the Green Fluorescent Protein (GFP gene expression. As the biocompatible and externally tunable polymer shells possess the capability to control the QD packing density at nanometer scales, the resulting luminescence efficiency of the nanostructures, besides reducing the cytotoxic potential, may be suitable for various biomedical applications.

  13. Escherichia coli pyomyositis in an immunocompromised host.

    Science.gov (United States)

    Sharma, Umesh; Schwan, William R; Agger, William A

    2011-08-01

    Pyomyositis due to Escherichia coli (E. coil) is rarely reported in immunocompromised patients with hematological malignancy. We present a case report of a 34-year-old man who developed E. coli pyomyositis as a complication of acute myelogenous leukemia (AML). Magnetic resonance imaging (MRI) of the right hip suggested myofascial infection of the gluteal muscles, and a needle muscle aspiration grew E. coli phylogenetic group B2. The patient responded to intravenous piperacillin/tazobactam followed by prolonged oral levofloxacin. Pyomyositis should be suspected in all immunocompromised patients complaining of muscle pain and may exhibit signs of localized muscle infection. Appropriate antibiotic therapy targeting fluoroquinolone-resistant E. coli should be considered for initial empiric therapy of pyomyositis in immunocompromised patients.

  14. Infectious endocarditis caused by Escherichia coli

    DEFF Research Database (Denmark)

    Lauridsen, Trine Kiilerich; Arpi, Magnus; Fritz-Hansen, Thomas

    2011-01-01

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

  15. Hydrogen production by recombinant Escherichia coli strains

    Science.gov (United States)

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

    2012-01-01

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

  16. Vaginal Lactobacillus isolates inhibit uropathogenic Escherichia coli.

    OpenAIRE

    Atassi , Fabrice; Brassart , Dominique; Grob , Philipp; Graf , Federico; Servin , Alain ,

    2006-01-01

    The purpose of this study was to investigate the antibacterial activities of Lactobacillus jensenii KS119.1 and KS121.1, and Lactobacillus gasserii KS120.1 and KS124.3 strains isolated from the vaginal microflora of healthy women, against uropathogenic, diffusely adhering Afa/Dr Escherichia coli (Afa/Dr DAEC) strains IH11128 and 7372 involved in recurrent cystitis. We observed that some of the Lactobacillus isolates inhibited the growth and decreased the viability of E. coli IH11128 and 7372....

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

    Directory of Open Access Journals (Sweden)

    Ancuta Mihaela Rotar

    2013-11-01

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

  18. Antioxidant and antibacterial effects of laurus nobilis aqueous extract again Staphylococcus aureus and Escherichia coli

    Directory of Open Access Journals (Sweden)

    B. Azimzadeh

    2017-05-01

    Full Text Available Some medical plants which are rich in phenolic compounds (flavnoieds, tannis and anthocyanin have drawn increasing attention as the most important naturanal antioxidant source by many developed countries. Laurus nobilis is one of the medical plants that grows in various regions of Iran. This plants is known to have many benefits and medical properties such as diuretics and mosaics. Also, this plant is used in treatment of gastrointestinal problems, especialy and it is effectieve in elimination of stomach gas. In this experiment, we studied antioxidant and antibacterial effects of Laurus nobilis plant. To this purpose, the efficiency of aqueous solvent extract, phenolic compounds, DPPH radical scavenging and ferric-reducing power and ABTS free radical scavenging were examined. Antibacterial characteristics of aqueous extract was evaluated on Staphylococcus aureus and Escherichiacoli. The result shows that the aqueous extract of Lauros nobilis has 14/8% extraction efficiency with high rate of phenolic (99/9±9/95 and the lowest IC50 in DPPH test (2/813 and the high rate of ferric reducing power (22/15±2/10 and ABTS free radical scavenging (22/87±2/03. The result of antibacterial test also indicates that aqueous extract has high antibacterial effect on Staphylococcus aureus (18±0 and E. Coli (18±0 mm.These facts show high antioxidant and antibacterial activity of laurel’s extract.

  19. Energetics of sodium efflux from Escherichia coli

    International Nuclear Information System (INIS)

    Borbolla, M.G.; Rosen, B.P.

    1984-01-01

    When energy-starved cells of Escherichia coli were passively loaded with 22 Na+, efflux of sodium could be initiated by addition of a source of metabolic energy. Conditions were established where the source of energy was phosphate bond energy, an electrochemical proton gradient, or both. Only an electrochemical proton gradient was required for efflux from intact cells. These results are consistent with secondary exchange of Na+ for H+ catalyzed by a sodium/proton antiporter

  20. Effects of Bos taurus autosome 9-located quantitative trait loci haplotypes on the disease phenotypes of dairy cows with experimentally induced Escherichia coli mastitis

    DEFF Research Database (Denmark)

    Khatun, Momena; Sørensen, Peter; Jørgensen, Hanne Birgitte Hede

    2013-01-01

    Several quantitative trait loci (QTL) affecting mastitis incidence and mastitis-related traits such as somatic cell score exist in dairy cows. Previously, QTL haplotypes associated with susceptibility to Escherichia coli mastitis in Nordic Holstein-Friesian (HF) cows were identified on Bos taurus...... autosome 9. In the present study, we induced experimental E. coli mastitis in Danish HF cows to investigate the effect of 2 E. coli mastitis-associated QTL haplotypes on the cows' disease phenotypes and recovery in early lactation. Thirty-two cows were divided in 2 groups bearing haplotypes with either low...... the HH group did. However, we also found interactions between the effects of haplotype and biopsy for body temperature, heart rate, and PMNL. In conclusion, when challenged with E. coli mastitis, HF cows with the specific Bos taurus autosome 9-located QTL haplotypes were associated with differences...

  1. Gene encoding virulence markers among Escherichia coli isolates ...

    African Journals Online (AJOL)

    River water sources and diarrhoeic stools of residents in the Venda Region, Limpopo Province of South Africa were analysed for the prevalence of Escherichia coli (E. coli) and the presence of virulence genes among the isolates. A control group of 100 nondiarrhoeic stool samples was included. Escherichia coli was ...

  2. Toxicity of TiO2 nanoparticles to Escherichia coli: effects of particle size, crystal phase and water chemistry.

    Directory of Open Access Journals (Sweden)

    Xiuchun Lin

    Full Text Available Controversial and inconsistent results on the eco-toxicity of TiO2 nanoparticles (NPs are commonly found in recorded studies and more experimental works are therefore warranted to elucidate the nanotoxicity and its underlying precise mechanisms. Toxicities of five types of TiO2 NPs with different particle sizes (10∼50 nm and crystal phases were investigated using Escherichia coli as a test organism. The effect of water chemistry on the nanotoxicity was also examined. The antibacterial effects of TiO2 NPs as revealed by dose-effect experiments decreased with increasing particle size and rutile content of the TiO2 NPs. More bacteria could survive at higher solution pH (5.0-10.0 and ionic strength (50-200 mg L(-1 NaCl as affected by the anatase TiO2 NPs. The TiO2 NPs with anatase crystal structure and smaller particle size produced higher content of intracellular reactive oxygen species and malondialdehyde, in line with their greater antibacterial effect. Transmission electron microscopic observations showed the concentration buildup of the anatase TiO2 NPs especially those with smaller particle sizes on the cell surfaces, leading to membrane damage and internalization. These research results will shed new light on the understanding of ecological effects of TiO2 NPs.

  3. Toxicity of TiO2 Nanoparticles to Escherichia coli: Effects of Particle Size, Crystal Phase and Water Chemistry

    Science.gov (United States)

    Lin, Xiuchun; Li, Jingyi; Ma, Si; Liu, Gesheng; Yang, Kun; Tong, Meiping; Lin, Daohui

    2014-01-01

    Controversial and inconsistent results on the eco-toxicity of TiO2 nanoparticles (NPs) are commonly found in recorded studies and more experimental works are therefore warranted to elucidate the nanotoxicity and its underlying precise mechanisms. Toxicities of five types of TiO2 NPs with different particle sizes (10∼50 nm) and crystal phases were investigated using Escherichia coli as a test organism. The effect of water chemistry on the nanotoxicity was also examined. The antibacterial effects of TiO2 NPs as revealed by dose-effect experiments decreased with increasing particle size and rutile content of the TiO2 NPs. More bacteria could survive at higher solution pH (5.0–10.0) and ionic strength (50–200 mg L−1 NaCl) as affected by the anatase TiO2 NPs. The TiO2 NPs with anatase crystal structure and smaller particle size produced higher content of intracellular reactive oxygen species and malondialdehyde, in line with their greater antibacterial effect. Transmission electron microscopic observations showed the concentration buildup of the anatase TiO2 NPs especially those with smaller particle sizes on the cell surfaces, leading to membrane damage and internalization. These research results will shed new light on the understanding of ecological effects of TiO2 NPs. PMID:25310452

  4. Effective inhibition of lytic development of bacteriophages λ, P1 and T4 by starvation of their host, Escherichia coli

    Directory of Open Access Journals (Sweden)

    Węgrzyn Alicja

    2007-02-01

    Full Text Available Abstract Background Bacteriophage infections of bacterial cultures cause serious problems in genetic engineering and biotechnology. They are dangerous not only because of direct effects on the currently infected cultures, i.e. their devastation, but also due to a high probability of spreading the phage progeny throughout a whole laboratory or plant, which causes a real danger for further cultivations. Therefore, a simple method for quick inhibition of phage development after detection of bacterial culture infection should be very useful. Results Here, we demonstrate that depletion of a carbon source from the culture medium, which provokes starvation of bacterial cells, results in rapid inhibition of lytic development of three Escherichia coli phages, λ, P1 and T4. Since the effect was similar for three different phages, it seems that it may be a general phenomenon. Moreover, similar effects were observed in flask cultures and in chemostats. Conclusion Bacteriophage lytic development can be inhibited efficiently by carbon source limitation in bacterial cultures. Thus, if bacteriophage contamination is detected, starvation procedures may be recommended to alleviate deleterious effects of phage infection on the culture. We believe that this strategy, in combination with the use of automated and sensitive bacteriophage biosensors, may be employed in the fermentation laboratory practice to control phage outbreaks in bioprocesses more effectively.

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

    OpenAIRE

    Toma, Claudia; Lu, Yan; Higa, Naomi; Nakasone, Noboru; Chinen, Isabel; Baschkier, Ariela; Rivas, Marta; Iwanaga, Masaaki

    2003-01-01

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

  6. Effect of signal peptide on stability and folding of Escherichia coli thioredoxin.

    Directory of Open Access Journals (Sweden)

    Pranveer Singh

    Full Text Available The signal peptide plays a key role in targeting and membrane insertion of secretory and membrane proteins in both prokaryotes and eukaryotes. In E. coli, recombinant proteins can be targeted to the periplasmic space by fusing naturally occurring signal sequences to their N-terminus. The model protein thioredoxin was fused at its N-terminus with malE and pelB signal sequences. While WT and the pelB fusion are soluble when expressed, the malE fusion was targeted to inclusion bodies and was refolded in vitro to yield a monomeric product with identical secondary structure to WT thioredoxin. The purified recombinant proteins were studied with respect to their thermodynamic stability, aggregation propensity and activity, and compared with wild type thioredoxin, without a signal sequence. The presence of signal sequences leads to thermodynamic destabilization, reduces the activity and increases the aggregation propensity, with malE having much larger effects than pelB. These studies show that besides acting as address labels, signal sequences can modulate protein stability and aggregation in a sequence dependent manner.

  7. Effect of signal peptide on stability and folding of Escherichia coli thioredoxin.

    Science.gov (United States)

    Singh, Pranveer; Sharma, Likhesh; Kulothungan, S Rajendra; Adkar, Bharat V; Prajapati, Ravindra Singh; Ali, P Shaik Syed; Krishnan, Beena; Varadarajan, Raghavan

    2013-01-01

    The signal peptide plays a key role in targeting and membrane insertion of secretory and membrane proteins in both prokaryotes and eukaryotes. In E. coli, recombinant proteins can be targeted to the periplasmic space by fusing naturally occurring signal sequences to their N-terminus. The model protein thioredoxin was fused at its N-terminus with malE and pelB signal sequences. While WT and the pelB fusion are soluble when expressed, the malE fusion was targeted to inclusion bodies and was refolded in vitro to yield a monomeric product with identical secondary structure to WT thioredoxin. The purified recombinant proteins were studied with respect to their thermodynamic stability, aggregation propensity and activity, and compared with wild type thioredoxin, without a signal sequence. The presence of signal sequences leads to thermodynamic destabilization, reduces the activity and increases the aggregation propensity, with malE having much larger effects than pelB. These studies show that besides acting as address labels, signal sequences can modulate protein stability and aggregation in a sequence dependent manner.

  8. The Effect of Growth Promoter Feed Additives on Performance of Broilers Challenged With Escherichia coli

    Directory of Open Access Journals (Sweden)

    A.R Valipouri

    2012-01-01

    Full Text Available A total of 528 day-old Ross 308 male broilers were used to study the effect of antibiotic, probiotic, prebiotic and organic acid on performance, cecal Coliform load and internal organs’ weight. The chickens were placed into 6 groups with 4 replicates and 22 chickens per pen. Six dietary treatments included: 1 negative control as basal diet without any antibiotic growth promoter and coccidiostat (Control, 2 Diet 1+ 0.9 g/kg Primalac® (Primalac, 3 Diet 1+0.1 g/kg Bactocell® (Bactocell, 4 Diet 1+15ppm virginiamycin (Virginiamycin, 5 Diet 1+2 g/kg Fermacto® (Fermacto, and 6 Diet 1+2 g/kg Formycin Gold® (Formycin. At day 7 all chickens were orally gavaged with a 0.5 mL of 107 cfu/mL of mixed culture of pathogenic E. coli (O2K12 and O78K80 verified for presence of genes including stx1, stx2, eaeA and hlyA. Eight chickens from each group were euthanized for detection of the challenged bacteria in liver, spleen and cecum content at days 14, 28 and 42. Overall weight gain (P

  9. Photochemistry and photobiology of 5-azacytidine: Effect of repair on photostabilization of Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Hradecna, Z [Ceskoslovenska Akademie Ved, Brno. Biofysikalni Ustav; Kittler, L; Loeber, G [Akademie der Wissenschaften der DDR, Jena. Zentralinstitut fuer Mikrobiologie und Experimentelle Therapie

    1978-10-01

    The photochemical stability of the anomalous nucleic acid base 5-azacytidine (z/sup 5/Cyd) on irradiation at 254 nm is by about one order of magnitude less than that of cytidine (Cyd). Contrary to the photochemical behaviour, incorporation of z/sup 5/Cyd into the nucleic acids of E.coli strains SR 20 (uvr/sup +/ rec/sup +/), SR 74 (uvr/sup +/ rec/sup -/) and SR 22 (uvr/sup -/ rec/sup +/) produced a higher resistance to UV light. Only the SR 73 (uvr/sup -/ rec/sup -/) strain was shown to have an increased UV sensitivity. This latter finding is in accord with the photochemical properties of z/sup 5/Cyd. The results led to the conclusion that excision and recombination repair processes contribute to the observable protective effect. The fact that inhibition of excission repair by caffeine or proflavine of the mutant uvr/sup +/ rec/sup -/changes protection into sensitization supports this idea.

  10. Effects of probiotic Escherichia coli Nissle 1917 on expression of cytochromes P450 along the gastrointestinal tract of male rats

    Czech Academy of Sciences Publication Activity Database

    Matušková, Z.; Tunková, A.; Anzenbacherová, E.; Večeřa, R.; Šiller, M.; Tlaskalová-Hogenová, Helena; Zídek, Zdeněk; Anzenbacher, P.

    2010-01-01

    Roč. 31, č. 2 (2010), s. 46-50 ISSN 0172-780X R&D Projects: GA ČR GA305/08/0535 Institutional research plan: CEZ:AV0Z50200510; CEZ:AV0Z50390512 Keywords : probiotic * Escherichia coli * cytochrome P450 Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 1.621, year: 2010

  11. Effect of gyrB-mediated changes in chromosome structure on killing of Escherichia coli by ultraviolet light: experiments with strains differing in deoxyribonucleic acid repair capacity

    International Nuclear Information System (INIS)

    von Wright, A.; Bridges, B.A.

    1981-01-01

    Mutations at the gyrB locus were found to decrease the degree of supercoiling of the Escherichia coli chromosome. The effect of a gyrB mutation on the repair of ultraviolet-induced deoxyribonucleic acid damage was studied by following the killing of strains of E. coli K-12 proficient and deficient in deoxyribonucleic acid repair. The effectiveness of both excision and postreplication types of deoxyribonucleic acid repair was found to be altered by this mutation, the former being apparently enhanced and the latter impaired

  12. The effectiveness of three home products in cleaning and disinfection of Staphylococcus aureus and Escherichia coli on home environmental surfaces.

    Science.gov (United States)

    Goodyear, N; Brouillette, N; Tenaglia, K; Gore, R; Marshall, J

    2015-11-01

    The objectives of this study were to investigate three products for: (i) cleaning effectiveness on two common household surfaces, and (ii) disinfection effectiveness against two common bacteria. Products included conventional ('bleach'), environmentally preferable (EP), do-it-yourself (DIY: distilled white vinegar, club soda, tea tree oil), 24-h old DIY, and individual DIY components in dilution. For cleaning ceramic, no product was effective (≥85% removal of Hucker's soil), however, DIY performed better than EP and bleach. On stainless, only DIY failed to meet the standard. For disinfection, bleach and EP achieved ≥5·00 log10 reductions under all conditions. DIY and components were more active against Escherichia coli than Staphylococcus aureus but only fresh DIY and 50% vinegar achieved ≥5·00 log10 reductions. EP is an effective alternative to bleach. DIY may be an adequate alternative for cleaning ceramic and for household use, where complete elimination of micro-organisms is unnecessary; however, it must be freshly prepared each day. This is the first report of performance of purportedly safer alternatives for both cleaning and disinfection for use in home health care. The EP product and DIY are potential alternatives for some household uses. © 2015 The Society for Applied Microbiology.

  13. Deuterium incorporation into Escherichia-coli proteins

    DEFF Research Database (Denmark)

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

    1986-01-01

    Neutron small-angle scattering studies of single protein subunits in a protein-DNA complex require the adjustment of the neutron scattering-length densities of protein and DNA, which is attainable by specific deuteration of the protein. The neutron scattering densities of unlabelled DNA and DNA......-dependent RNA polymerase of Escherichia coli match when RNA polymerase is isolated from cells grown in a medium containing 46% D2O and unlabelled glucose as carbon source. Their contrasts vanish simultaneously in a dialysis buffer containing 65% D2O. An expression was evaluated which allows the calculation...... of the degree of deuteration and match point of any E. coli protein from the D2O content of the growth medium, taking the 2H incorporation into RNA polymerase amino acids to be representative for all amino acids in E. coli proteins. The small-angle scattering results, on which the calculation of the degree...

  14. Antibacterial effect of silver nanoparticles and capsaicin against MDR-ESBL producing Escherichia coli: An in vitro study

    Directory of Open Access Journals (Sweden)

    Debasish Kar

    2016-10-01

    Full Text Available Objective: To evaluate the antibacterial property of silver nanoparticles (AgNPs and capsaicin against multidrug resistant (MDR and extended spectrum beta-lactamase (ESBL producing Escherichia coli of bovine and poultry origin. Methods: Antibacterial efficacy of AgNPs and capsaicin was measured using broth dilution method. Five MDR-ESBL producing E. coli isolates of poultry (PEC4, PEC6, PEC15 and PEC16 and cattle mastitis origin (MEC2 were taken to evaluate the antibacterial effect of AgNPs and capsaicin. Results: At 50 mmol/L AgNPs, the viability of MDR of bacterial pathogens was reduced to almost 80%–90% and at 1000 mmol/L, the viability went down to 0%–3%. The minimum inhibitory concentration (MIC50 of AgNPs against these MDR-ESBL producing isolates was found to vary between 172–218 mmol/L whereas the MIC80 varied between 450–640 mmol/L. Capsaicin showed more prominent bactericidal effect and only at 2.5 mmol/L concentration, the viability was shown to be reduced by 20%–35% whereas at 7.5 mmol/L concentration, there was approximately 60% reduction in viability. Further at 25 mmol/L concentration, the viability was reduced to 0%–8%. The MIC50 and MIC80 of capsaicin against these MDRESBL producing isolates were found to vary between 4.6–7.5 mmol/L and 10.9–16.9 mmol/L, respectively. Conclusions: The results point out that capsaicin and AgNPs could be of use in treating ESBL infection.

  15. Nanotextile membranes for bacteria Escherichia coli capturing

    Directory of Open Access Journals (Sweden)

    Jaroslav Lev

    2010-01-01

    Full Text Available The article describes an experimental study dealing with the possibility of nanotextile materials usa­ge for microbiologically contaminated water filtration. The aim of the study is to verify filtration ability of different nanotextile materials and evaluate the possibilities of practical usage. Good detention ability of these materials in the air filtration is the presumption for nanotextile to be used for bacteria filtration from a liquid. High nanotextile porosity with the nanotextile pores dimensions smaller than a bacteria size predicates the possibility of a successful usage of these materials. For the experiment were used materials made from electrospinning nanofibres under the label PA612, PUR1, PUR2 s PUR3 on the supporting unwoven textiles (viscose and PP. As a model simulation of the microbial contamination, bacteria Escherichia coli was chosen. Contaminated water was filtered during the overpressure activity of 105Pa on the input side of the filter from the mentioned material. After three-day incubation on the nutrient medium, cultures found in the samples before and after filtration were compared. In the filtrated water, bacteria E. coli were indicated, which did not verify the theoretical presumptions about an absolut bacteria detention. However, used materials caught at least 94% of bacteria in case of material PUR1 and up to 99,996% in case of material PUR2. These results predict the possibility of producing effective nanotextile filters for microbiologically contaminated water filtration.Recommendation: For the production of materials with better filtrating qualities, experiments need to be done, enabling better understanding of the bacteria detention mechanisms on the nanotextile material, and parameters of the used materials that influence the filtrating abilities need to be verified.

  16. Effect of human polymorphonuclear and mononuclear leukocytes on chromosomal and plasmid DNA of Escherichia coli. Role of acid DNase

    International Nuclear Information System (INIS)

    Rozenberg-Arska, M.; van Strijp, J.A.; Hoekstra, W.P.; Verhoef, J.

    1984-01-01

    Phagocytosis and killing by polymorphonuclear and mononuclear leukocytes are important host resistance factors against invading microorganisms. Evidence showing that killing is rapidly followed by degradation of bacterial components is limited. Therefore, we studied the fate of Escherichia coli DNA following phagocytosis of E. coli by polymorphonuclear and mononuclear leukocytes. [ 3 H]Thymidine-labeled, unencapsulated E. coli PC2166 and E. coli 048K1 were incubated in serum, washed, and added to leukocytes. Uptake and killing of the bacteria and degradation of DNA were measured. Although phagocytosis and killing by mononuclear leukocytes was less efficient than that by polymorphonuclear leukocytes, only mononuclear leukocytes were able to degrade E. coli PC2166 DNA. Within 2 h, 60% of the radioactivity added to mononuclear leukocytes was released into the supernate, of which 40% was acid soluble. DNA of E. coli 048K1 was not degraded. To further analyze the capacity of mononuclear leukocytes to degrade E. coli DNA, chromosomal and plasmid DNA was isolated from ingested bacteria and subjected to agarose gel-electrophoresis. Only chromosomal DNA was degraded after phagocytosis. Plasmid DNA of E. coli carrying a gene coding for ampicillin resistance remained intact for a 2-h period after ingestion, and was still able to transform recipient E. coli cells after this period. Although we observed no DNA degradation during phagocytosis by polymorphonuclear leukocytes, lysates of both polymorphonuclear and mononuclear leukocytes contained acid-DNase activity with a pH optimum of 4.9. However, the DNase activity of mononuclear leukocytes was 20 times higher than that of polymorphonuclear leukocytes. No difference was observed between DNase activity from polymorphonuclear and mononuclear leukocytes from a chronic granulomatous disease patient with DNase activity from control polymorphonuclear and mononuclear leukocytes

  17. Chemical Composition of Herbal Macerates and Corresponding Commercial Essential Oils and Their Effect on Bacteria Escherichia coli

    Directory of Open Access Journals (Sweden)

    Marietta Białoń

    2017-11-01

    Full Text Available This study addresses the chemical composition of some commercial essential oils (clove, juniper, oregano, and marjoram oils, as well as appropriate herbal extracts obtained in the process of cold maceration and their biological activity against selected Escherichia coli strains: E. coli ATTC 25922, E. coli ATTC 10536, and E. coli 127 isolated from poultry waste. On the basis of the gas chromatography-mass spectrometry (GCMS analysis, it was found that the commercial essential oils revealed considerable differences in terms of the composition and diversity of terpenes, terpenoids and sesquiterpenes as compared with the extracts obtained from plant material. The commercial clove, oregano, and marjoram oils showed antibacterial properties against all the tested strains of E. coli. However, these strains were not sensitive to essential oils obtained from the plant material in the process of maceration. The tested strains of E. coli show a high sensitivity, mainly against monoterpenes (α-pinene, β-pinene, α,β,γ-terpinene, limonene and some terpenoids (thymol, carvacrol. The commercial juniper oil contained mainly monoterpenes and monoterpenoids, while the extracts contained lower amounts of monoterpenes and high amounts of sesquiterpenes—the anti-microbiotic properties of the juniper herbal extract seem to be caused by the synergistic activity of mono- and sesquiterpenes.

  18. Effectiveness of Sanitizer D7(TM) against Escherichia coli O157:H7 and Salmonella biofilms

    Science.gov (United States)

    Introduction: Biofilm formation by E. coli O157:H7 and Salmonella enterica at meat processing plants poses a serious risk of meat product contamination. Available studies have shown that many common sanitizers were unable to completely eradicate biofilms by these foodborne pathogens due to the 3-dim...

  19. Antimicrobial effect of Al2O3, Ag and Al2O3/Ag thin films on Escherichia coli and Pseudomonas putida

    International Nuclear Information System (INIS)

    Angelov, O; Stoyanova, D; Ivanova, I; Todorova, S

    2016-01-01

    The influence of Al 2 O 3 , Ag and Al 2 O 3 /Ag thin films on bacterial growth of Gramnegative bacteria Pseudomonas putida and Escherichia coli is studied. The nanostructured thin films are deposited on glass substrates without intentional heating through r.f. magnetron sputtering in Ar atmosphere of Al 2 O 3 and Ag targets or through sequential sputtering of Al 2 O 3 and Ag targets, respectively. The individual Ag thin films (thickness 8 nm) have a weak bacteriostatic effect on Escherichia coli expressed as an extended adaptive phase of the bacteria up to 5 hours from the beginning of the experiment, but the final effect is only 10 times lower bacterial density than in the control. The individual Al 2 O 3 film (20 nm) has no antibacterial effect against two strains E. coli - industrial and pathogenic. The Al 2 O 3 /Ag bilayer films (Al 2 O 3 20 nm/Ag 8 nm) have strong bactericidal effect on Pseudomonas putida and demonstrate an effective time of disinfection for 2 hours. The individual films Al2O3 and Ag have not pronounced antibacterial effect on Pseudomonas putida . A synergistic effect of Al2O3/Ag bilayer films in formation of oxidative species on the surface in contact with the bacterial suspension could be a reason for their antimicrobial effect on E. coli and P. putida . (paper)

  20. Rational Design of Novel Allosteric Dihydrofolate Reductase Inhibitors Showing Antibacterial Effects on Drug-Resistant Escherichia coli Escape Variants.

    Science.gov (United States)

    Srinivasan, Bharath; Rodrigues, João V; Tonddast-Navaei, Sam; Shakhnovich, Eugene; Skolnick, Jeffrey

    2017-07-21

    In drug discovery, systematic variations of substituents on a common scaffold and bioisosteric replacements are often used to generate diversity and obtain molecules with better biological effects. However, this could saturate the small-molecule diversity pool resulting in drug resistance. On the other hand, conventional drug discovery relies on targeting known pockets on protein surfaces leading to drug resistance by mutations of critical pocket residues. Here, we present a two-pronged strategy of designing novel drugs that target unique pockets on a protein's surface to overcome the above problems. Dihydrofolate reductase, DHFR, is a critical enzyme involved in thymidine and purine nucleotide biosynthesis. Several classes of compounds that are structural analogues of the substrate dihydrofolate have been explored for their antifolate activity. Here, we describe 10 novel small-molecule inhibitors of Escherichia coli DHFR, EcDHFR, belonging to the stilbenoid, deoxybenzoin, and chalcone family of compounds discovered by a combination of pocket-based virtual ligand screening and systematic scaffold hopping. These inhibitors show a unique uncompetitive or noncompetitive inhibition mechanism, distinct from those reported for all known inhibitors of DHFR, indicative of binding to a unique pocket distinct from either substrate or cofactor-binding pockets. Furthermore, we demonstrate that rescue mutants of EcDHFR, with reduced affinity to all known classes of DHFR inhibitors, are inhibited at the same concentration as the wild-type. These compounds also exhibit antibacterial activity against E. coli harboring the drug-resistant variant of DHFR. This discovery is the first report on a novel class of inhibitors targeting a unique pocket on EcDHFR.

  1. In vitro Effectiveness of Commercial Bacteriophage Cocktails on Diverse Extended-Spectrum Beta-Lactamase Producing Escherichia coli Strains.

    Science.gov (United States)

    Gundogdu, Aycan; Bolkvadze, Darajen; Kilic, Huseyin

    2016-01-01

    The objective of this study is to determine the in vitro susceptibility of Georgian bacteriophage cocktails on multidrug resistant (MDR) extended-spectrum beta-lactamase producing Escherichia coli (ESBL-EC) isolated from patients' blood and urine cultures. A total of 615 E. coli isolates were included in this study. Phene Plate (PhP)-typing and phylogenetic grouping were used for the typing. Antimicrobial resistance profiles and ESBL production of all isolates were confirmed according to Clinical and Laboratory Standards Institute (CLSI) criteria. The activities of four bacteriophage cocktails (Enko-phage, SES-bacteriophage, Pyo-bacteriophage, and Intesti-bacteriophage) were determined against 142 ESBL-EC using in vitro spot tests. According to this, Enko-phage were active against 87.3% of the tested strains while that ratio was 81.7% for Intesti-bacteriophage, 81.7% for Pyo-bacteriophage, and 59.2% for SES-bacteriophage cocktails. Based on the contingency tests, the phage cocktails were observed to be statistically significantly ( p < 0.001) more effective on ESBL-EC strains belonging to phylogenetic groups D and B2. The employed phage cocktails were found to be affective against all tested resistant types. These results are promising especially for the infections that are caused by MDR pathogens that are difficult to treat. As this is a preliminary step to the potential clinical trials to be designed for the country, in vitro confirmation of their success on a MDR ESBL-EC collection should be accepted as an initial action, which is encouraging to consider clinical trials of phage therapy especially in countries which are not introduce phage therapy.

  2. in vitro effectiveness of commercial bacteriophage cocktails on diverse extended spectrum beta-lactamase (ESBL producing Escherichia coli strains

    Directory of Open Access Journals (Sweden)

    Aycan Gundogdu

    2016-11-01

    Full Text Available The objective of this study is to determine the in vitro susceptibility of Georgian bacteriophage cocktails on multi-drug resistant extended-spectrum β-lactamase producing Escherichia coli (ESBL-EC isolated from patients' blood and urine cultures. 615 E. coli isolates were included in this study. PhP-typing and phylogenetic grouping were used for the typing. Antimicrobial resistance profiles and ESBL production of all isolates were confirmed according to CLSI criteria. The activities of four bacteriophage cocktails (Enko-phage, SES-bacteriophage, Pyo-bacteriophage and Intesti-bacteriophage were determined against 142 ESBL- EC using in vitro spot tests. According to this, Enko-phage were active against 87.3% of the tested strains while that ratio was 81.7% for intesti-bacteriophage, 81.7% for Pyo-bacteriophage and 59.2% for SES-bacteriophage cocktails. Based on the contingency tests, the phage cocktails were observed to be statistically significantly (p<0.001 more effective on ESBL-EC strains belonging to phylogenetic groups D and B2. The employed phage cocktails were found to be affective against all tested resistant types. These results are promising especially for the infections that are caused by multi-drug resistant pathogens that are difficult to treat. As this is a preliminary step to the potential clinical trials to be designed for the country, in vitro confirmation of their success on a multi-drug-resistant ESBL-EC collection should be accepted as an initial action, which is encouraging to consider clinical trials of phage therapy especially in countries which are not introduce phage therapy.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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.

  4. Escherichia coli in broiler chickens with airsacculitis

    Directory of Open Access Journals (Sweden)

    Leandro S. Machado

    2014-09-01

    Full Text Available ABSTRACT. Machado L.S., do Nascimento E.R., Pereira V.L.A., Abreu D.L.C., Gouvea R. & Santos L.M.M. 2014. [Escherichia coli in broiler chickens with airsacculitis.] Escherichia coli em frangos de corte com aerossaculite. Revista Brasileira de Medicina Veterinária, 36(3:261-265, 2014. Departamento de Medicina Veterinária Preventiva e Saúde Pública, Faculdade de Veterinária, Universidade Federal Fluminense, Rua Dr. Vital Brazil Filho 64, Vital Brazil, Niterói, RJ 24230-340, Brazil. E-mail: leandromachadovet@yahoo.com.br The Brazilian poultry industry grows each year and becomes increasingly representative in the production and export of products. The health care with poultry have accompanied and favored this evolution, however, respiratory agents that affect the weight and carcass quality, continue to cause great damage to the poultry industry. Airsacculitis is considered the main cause of total and partial condemnation of carcasses of broilers, and has been attributed to Mycoplasmosis mostly caused by Mycoplasma gallisepticum (MG and Mycoplasma synoviae (MS and Escherichia coli. The aim of this study was to relate the positivity of MG / MS and E. coli detected by PCR as a risk factor for airsacculitis in condemnation of broilers in Health Inspection Service. We studied 30 broiler poultry slaughtered in a slaughterhouse under Federal Sanitary Inspection, located in the State of Rio de Janeiro. 30 chickens were randomly collected from different lots and tracheas obtained in each PCR. DNA was extracted by phenol-chloroform method and amplified using pairs of “primer”specific for MG, MS and E. coli. Of the 30 chickens analyzed by PCR, 30% (9/30 had lesions in air sacs. None of the birds showed infection with MG and/or MS PCR, however 33.3% (3/9 birds were positive for airsacculitis iss gene from E.coli. E.coli found in broiler chickens that were negative for mycoplasma airsacculitis, implying the presence of such bacteria may be sufficient

  5. Adjuvant effect of Gantrez®AN nanoparticles during oral vaccination of piglets against F4+enterotoxigenic Escherichia coli.

    Science.gov (United States)

    Vandamme, Katrien; Melkebeek, Vesna; Vesna, Melkebeek; Cox, Eric; Eric, Cox; Remon, Jean Paul; Paul, Remon Jean; Vervaet, Chris; Chris, Vervaet

    2011-02-15

    In this study, the adjuvanticity of methylvinylether-co-maleic anhydride (Gantrez(®)AN) nanoparticles (NP) was investigated in an oral immunisation experiment of pigs against F4+enterotoxigenic Escherichia coli (F4+ETEC). In addition, Wheat Germ Agglutinin (WGA)-coating of the nanoparticles was tested for enterocyte-targeting. Pigs were either vaccinated with F4 fimbriae, F4 encapsulated in Gantrez(®)AN NP, F4 encapsulated in Gantrez(®)AN NP coated with WGA or F4 fimbriae mixed with empty Gantrez(®)AN NP. Only vaccination with the combination of F4 mixed with empty Gantrez(®)AN NP improved protection against F4+ETEC infection. In addition, vaccination with this formulation also resulted in an F4-specific serum antibody response prior to F4+ETEC challenge. Encapsulation of F4 in Gantrez(®)AN NP only raised the serum antibody response after F4+ETEC challenge compared to soluble F4, but did not improve protection, whereas WGA-coating almost completely abolished the serum antibody response. These data indicate that nanoparticle effects after F4 encapsulation were of lesser importance for the adjuvant effect of Gantrez(®)AN NP, contrarily to the reactivity of the Gantrez(®)AN polymer used to prepare the nanoparticles. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Effects of coordination of diammineplatinum(II) with DNA on the activities of Escherichia coli DNA polymerase I

    International Nuclear Information System (INIS)

    Bernges, F.; Holler, E.

    1988-01-01

    The effects of the reaction of cis- and trans-diamminedichloroplatinum(II) with DNA have been measured with regard to DNA synthesis, 3'-5' exonuclease (proofreading), and 5'-3' exonuclease (repair) activities of Escherichia coli DNA polymerase I. Both isomers inhibit DNA synthetic activity of the polymerase through an increase in K/sub m/ values and a decrease in V/sub max/ values for platinated DNA but not for the nucleoside 5'-triphosphates as the varied substrates. The inhibition is a consequence of lowered binding affinity between platinated DNA and DNA polymerase, and of a platination-induced separation of template and primer strands. Strand separation enhances initial rates of 3'-5' excision of [ 3 H]dCMP from platinated DNA (proofreading), while total excision levels of nucleotides are decreased. In contrast to proofreading activity, the 5'-3' exonuclease activity (repair) discriminates between DNA which had reacted with cis- and with trans-diamminedichloroplatinum(II). While both initial rates and total excision are inhibited for the cis isomer, they are almost not affected for the trans isomer. This differential effect could explain why bacterial growth inhibition requires much higher concentrations of trans- than cis-diamminedichloroplatinum(II)

  7. Differential effects of near-UV and visible light on active transport and other membrane processes in Escherichia coli

    International Nuclear Information System (INIS)

    Sprott, G.D.; Martin, W.G.; Schneider, N.

    1976-01-01

    The effects of monochromatic near-UV and visible light on active transport and several other membrane processes in Escherichia coli were investigated. Using mercury lines at 366, 405, 435, 546 and 578 nm, large differential effects were observed. Transport systems with photosensitive initial rates of uptake were classified into three groups on the basis of wavelength dependence. Three, and possibly four photosensitizers may be involved; three active under aerobic conditions and the fourth in the absence of oxygen. Respiration rate exhibited the same sensitivity as one of the groups, suggesting that the active uptake of member amino acids (e.g. glycine) is largely dependent on oxidation energy. The photosensitivity of glycine transport at 405 nm was not the result of inhibition of the membrane-bound Ca-Mg adenosine triphosphates as shown using an isogenic mutant strain. Cell viability was not affected at the highly active wavelength, 405 nm. Photoeffects on transport of α-methylglucoside were minimal at 366 and 405 nm, contrasting to most of the amino acids investigated. The relative photosensitivity of respiration and several amino acid transport systems depended on carbon source. (author)

  8. Effects of burn with and without Escherichia coli infection in rats on intestinal vs. splenic T-cell responses.

    Science.gov (United States)

    Ravindranath, T; Al-Ghoul, W; Namak, S; Fazal, N; Durazo-Arvizu, R; Choudhry, M; Sayeed, M M

    2001-12-01

    To evaluate the effect of burn injury with and without an Escherichia coliseptic complication on T-cell proliferation, interleukin-2 production, and Ca(2+) signaling responses in intestinal Peyer's patch and splenic T cells. Prospective, randomized, sham-controlled animal study. University medical center research laboratory. Adult male Sprague-Dawley rats. Rats were subjected to a 30% total body surface area, full skin thickness burn. Infection in rats was induced via intraperitoneal inoculation of E. coli, 10(9) colony forming units/kg, with or without a prior burn. Rat Peyer's patch and splenic T lymphocytes were isolated by using a nylon wool cell purification protocol. T-cell proliferation, interleukin-2 production, and Ca(2+) signaling responses were measured after stimulation of cells with the mitogen, concanavalin A. T-cell proliferation was determined by measuring incorporation of (3)H-thymidine into T-cell cultures. Interleukin-2 production by T-cell cultures was measured by using enzyme-linked immunosorbent assay. Intracellular T-cell Ca2(+ )concentration, [Ca(2+)](i), was measured by the use of Ca(2+)-specific fluorescent label, fura-2, and its fluorometric quantification. [Ca(2+)](i) was also evaluated by the use of digital video imaging of fura-2 loaded individual T cells. T-cell proliferation and interleukin-2 production were suppressed substantially in both Peyer's patch and splenic T cells 3 days after either the initial burn alone or burn followed by the E. coli inoculation at 24 hrs after the initial burn. There seemed to be no demonstrable additive effects of E. coli infection on the effects produced by burn injury alone. The T-cell proliferation and interleukin-2 production suppressions with burn or burn-plus-infection insults were correlated with attenuated Ca(2+) signaling. E. coli infection alone suppressed T-cell proliferation in Peyer's patch but not in splenic T cells at 2 days postbacterial inoculation; E. coli infection had no effect on

  9. Profiling of Escherichia coli Chromosome database.

    Science.gov (United States)

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

    2008-01-01

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

  10. Epidemiology and clinical manifestations of enteroaggregative Escherichia coli

    DEFF Research Database (Denmark)

    Hebbelstrup Jensen, Betina; Olsen, Katharina E P; Struve, Carsten

    2014-01-01

    Enteroaggregative Escherichia coli (EAEC) represents a heterogeneous group of E. coli strains. The pathogenicity and clinical relevance of these bacteria are still controversial. In this review, we describe the clinical significance of EAEC regarding patterns of infection in humans, transmission...

  11. lactamases genes among0 Escherichia coli from patients with ...

    African Journals Online (AJOL)

    -lactamases (ESBLs) that mediate resistance to b-lactam drugs among Escherichia coli and other uropathogens have been reported worldwide. However, there is little information on the detection of ESBLs genes in E. coli from patients with ...

  12. Plasmid-Mediated Quinolone Resistance Genes in Escherichia coli ...

    African Journals Online (AJOL)

    Erah

    PMQR) genes and the prevalence of extended spectrum β-lactamase (ESBL) types in Escherichia coli clinical isolates. Methods: Sixty-one ESBL-producing urinary E. coli isolates were studied. An antibiotic susceptibility test was performed ...

  13. Arginine Coordination in Enzymatic Phosphoryl Transfer: Evaluation of the Effect of Arg166 Mutations in Escherichia Coli Alkaline Phosphatase

    International Nuclear Information System (INIS)

    O'Brien, P.J.; Lassila, J.K.; Fenn, T.D.; Zalatan, J.G.; Herschlag, D.

    2008-01-01

    Arginine residues are commonly found in the active sites of enzymes catalyzing phosphoryl transfer reactions. Numerous site-directed mutagenesis experiments establish the importance of these residues for efficient catalysis, but their role in catalysis is not clear. To examine the role of arginine residues in the phosphoryl transfer reaction, we have measured the consequences of mutations to arginine 166 in Escherichia coli alkaline phosphatase on hydrolysis of ethyl phosphate, on individual reaction steps in the hydrolysis of the covalent enzyme-phosphoryl intermediate, and on thio substitution effects. The results show that the role of the arginine side chain extends beyond its positive charge, as the Arg166Lys mutant is as compromised in activity as Arg166Ser. Through measurement of individual reaction steps, we construct a free energy profile for the hydrolysis of the enzyme-phosphate intermediate. This analysis indicates that the arginine side chain strengthens binding by ∼3 kcal/mol and provides an additional 1-2 kcal/mol stabilization of the chemical transition state. A 2.1 (angstrom) X-ray diffraction structure of Arg166Ser AP is presented, which shows little difference in enzyme structure compared to the wild-type enzyme but shows a significant reorientation of the bound phosphate. Altogether, these results support a model in which the arginine contributes to catalysis through binding interactions and through additional transition state stabilization that may arise from complementarity of the guanidinum group to the geometry of the trigonal bipyramidal transition state

  14. The effect of an extract from Ganoderma lucidum (reishi) on the labeling of blood constituents with technetium-99m and on the survival of Escherichia coli

    International Nuclear Information System (INIS)

    Agostinho, Raquel Terra; Santos Filho, Sebastiao David; Fonseca, Adenilson de Souza da; Bernardo-Filho, Mario; Missailidis, Sotiris

    2008-01-01

    This study evaluated effects of an aqueous extract of Ganoderma lucidum (reishi) on the labeling of blood constituents with technetium-99m ( 99m Tc) and on the survival of cultures of Escherichia coli treated with stannous chloride. Blood samples from Wistar rats were treated with reishi extract, radiolabeling procedure was performed, plasma (P), blood cells (BC) and insoluble (IF) and soluble (SF) fractions of P and BC were separated. The radioactivity was counted for the determination of the percentages of radioactivity (%ATI). Cultures of Escherichia coli AB1157 were treated with stannous chloride in the presence and absence of reishi extract. Blood samples and bacterial cultures treated with NaCl 0.9% were used as controls. Data indicated that reishi extract altered significantly (p 99 mTc and protecting bacterial cultures against oxidative damage induced by stannous chloride. (author)

  15. Effect of addition of organic waste on reduction of Escherichia coli during cattle feces composting under high-moisture condition.

    Science.gov (United States)

    Hanajima, Dai; Kuroda, Kazutaka; Fukumoto, Yasuyuki; Haga, Kiyonori

    2006-09-01

    To ensure Escherichia coli reduction during cattle feces composting, co-composting with a variety of organic wastes was examined. A mixture of dairy cattle feces and shredded rice straw (control) was blended with organic wastes (tofu residue, rice bran, rapeseed meal, dried chicken feces, raw chicken feces, or garbage), and composted using a bench-scale composter under the high-moisture condition (78%). The addition of organic waste except chicken feces brought about maximum temperatures of more than 55 degrees C and significantly reduced the number of E. coli from 10(6) to below 10(2)CFU/g-wet after seven days composting, while in the control treatment, E. coli survived at the same level as that of raw feces. Enhancements of the thermophilic phase and E. coli reduction were related to the initial amount of easily digestible carbon in mass determined as BOD. BOD value more than 166.2 mg O2/DMg brought about significant E. coli reduction.

  16. Bovine Leukemia Virus Infection in Dairy Cattle: Effect on Serological Response to Immunization against J5 Escherichia coli Bacterin

    Directory of Open Access Journals (Sweden)

    Ronald J. Erskine

    2011-01-01

    Full Text Available Thirteen bovine leukemia virus- (BLV- negative and 22 BLV-positive Holstein cows were immunized with J5 Escherichia coli bacterin at dry off, three weeks before calving, during the second week after calving, and three weeks after the third immunization. Serum was collected before the initial immunization, immediately before the third and fourth immunizations, and 21 days after the fourth immunization. Anti-J5 E. coli IgM, IgG1, and IgG2 titers were determined by ELISA. Anti-J5 E. coli IgM titers did not differ significantly (P=.98 between groups. Increases in anti-J5 E. coli IgG1 titers were higher in the BLV-negative cows (P=.057. Geometric mean anti-J5 E. coli IgG2 titers increased fourfold in the BLV-negative cows, which was significantly higher (P=.007 than the twofold increase in the BLV-positive cows. Cattle infected with BLV may have impaired serologic responses following immunization with J5 bacterin, and response may differ according to antibody isotype.

  17. Escherichia coli Attenuation by Fe Electrocoagulation in Synthetic Bengal Groundwater: Effect of pH and Natural Organic Matter.

    Science.gov (United States)

    Delaire, Caroline; van Genuchten, Case M; Nelson, Kara L; Amrose, Susan E; Gadgil, Ashok J

    2015-08-18

    Technologies addressing both arsenic and microbial contamination of Bengal groundwater are needed. Fe electrocoagulation (Fe-EC), a simple process relying on the dissolution of an Fe(0) anode to produce Fe(III) precipitates, has been shown to efficiently remove arsenic from groundwater at low cost. We investigated Escherichia coli (E. coli) attenuation by Fe-EC in synthetic Bengal groundwater as a function of Fe dosage rate, total Fe dosed, pH, and presence of natural organic matter (NOM). A 2.5 mM Fe dosage simultaneously achieved over 4-log E. coli attenuation and arsenic removal from 450 to below 10 μg/L. E. coli reduction was significantly enhanced at pH 6.6 compared to pH 7.5, which we linked to the decreased rate of Fe(II) oxidation at lower pH. 3 mg/L-C of NOM (Suwanee River fulvic acid) did not significantly affect E. coli attenuation. Live-dead staining and comparisons of Fe-EC with chemical coagulation controls showed that the primary mechanism of E. coli attenuation is physical removal with Fe(III) precipitates, with inactivation likely contributing as well at lower pH. Transmission electron microscopy showed that EC precipitates adhere to and bridge individual E. coli cells, resulting in large bacteria-Fe aggregates that can be removed by gravitational settling. Our results point to the promising ability of Fe-EC to treat arsenic and bacterial contamination simultaneously at low cost.

  18. Effect of ionizing radition on conjugative R plasmid in Escherichia coli

    International Nuclear Information System (INIS)

    Kmetova, M.; Puzova, H.; Rexa, R.

    1986-01-01

    Five-fold cyclic gamma irradiation of E. coli strain No. 214 with conjugative R plasmid with doses of 150 Gy, with the exception of chloramphenicol, did not essentially affect the expression of the examined determinants of resistance to antimicrobial substances (tetracycline, streptomycin, chloramphenicol, canamycin, ampicillin, sulfamethoxidine). The dose of 150 Gy from the first irradiation of the strain reduced the transfer frequency of the R plasmid approximately hundred-fold. After the second up to the fourth irradiation of the strain the transfer frequency went back to approximately its original value. (author)

  19. Translational coupling in Escherichia coli of a heterologous Bacillus subtilis-Escherichia coli gene fusion.

    OpenAIRE

    Zaghloul, T I; Doi, R H

    1986-01-01

    The efficient expression in Escherichia coli of the Tn9-derived chloramphenicol acetyltransferase (EC 2.3.1.28) gene fused distal to the promoter and N terminus of the Bacillus subtilis aprA gene was dependent on the initiation of translation from the ribosome-binding site in the aprA gene.

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

    Science.gov (United States)

    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...

  1. Chromosomal features of Escherichia coli serotype O2:K2, an avian pathogenic E. coli

    DEFF Research Database (Denmark)

    Jørgensen, Steffen L; Kudirkiene, Egle; Li, Lili

    2017-01-01

    Escherichia coli causing infection outside the gastrointestinal system are referred to as extra-intestinal pathogenic E. coli. Avian pathogenic E. coli is a subgroup of extra-intestinal pathogenic E. coli and infections due to avian pathogenic E. coli have major impact on poultry production econo...

  2. Rifampicin and chloramphenicol effects on DNA replication in ultraviolet-damaged Escherichia coli B/r WP2 thy trp

    International Nuclear Information System (INIS)

    Doudney, C.O.

    1976-01-01

    The antibiotic rifampicin, which blocks specifically RNA synthesis, limited DNA replication in Escherichia coli strain B/r WP2 thy trp after an increase of about 50% when added to the incubation medium at the time of replication initiation after ultraviolet fluences of 20 J/m 2 or 25 J/m 2 . Chloramphenicol, which blocks protein synthesis, did not limit DNA replication when added at initiation or any time after. The prolonged lag in DNA replication caused by ultraviolet was not itself responsible for the rifampicin limitation. When a lag of 30 min was caused by starvation for thymine, DNA was synthesized after readdition of thymine to an increase of 100% or more in rifampicin-containing medium. When chloramphenicol was added to an ultraviolet-exposed culture, the limiting effect of rifampicin alone was suppressed. This effect held even with a higher fluence (32.5 J/m 2 ), after which the ability to make DNA in the presence of rifampicin alone was slight. Maximum effect was obtained when the chloramphenicol was added to the ultraviolet-exposed, rifampicin-containing culture immediately before initiation of DNA replication. When rifampicin was present at a concentration of 150 μg/ml (2.2 x 10 -4 M), 3 μg/ml of chloramphenicol (9.2 x 10 -6 M) was as effective as 160 μg/ml (5.0 x 10 -4 M), thus eliminating the possibility that direct stoichiometric interaction of rifampicin and chloramphenicol molecules caused the effect

  3. Enteropathogenic Escherichia coli: foe or innocent bystander?

    Science.gov (United States)

    Hu, Jia; Torres, Alfredo G.

    2015-01-01

    Enteropathogenic Escherichia coli (EPEC) remain one the most important pathogens infecting children and they are one of the main causes of persistent diarrhea 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 diarrheal cases. However, occurrence of atypical EPEC (aEPEC; eae+ bfpA- stx-) in diarrheal and asymptomatic hosts has made investigators question the role of these pathogens in human disease. Current epidemiological data is helping answering the question whether EPEC is mainly a foe or an innocent bystander during infection. PMID:25726041

  4. Dynamics of chromosome segregation in Escherichia coli

    DEFF Research Database (Denmark)

    Nielsen, Henrik Jørck

    2007-01-01

    Since the 1960’es the conformation and segregation of the chromosome in Escherichia coli has been a subject of interest for many scientists. However, after 40 years of research, we still know incredibly little about how the chromosome is organized inside the cell, how it manages to duplicate...... this incredibly big molecule and separate the two daughter chromosomes and how it makes sure that the daughter cells receives one copy each. The fully extended chromosome is two orders of magnitude larger than the cell in which it is contained. Hence the chromosome is heavily compacted in the cell...

  5. Escherichia coli photoreactivating enzyme: purification and properties

    International Nuclear Information System (INIS)

    Snapka, R.M.; Sutherland, B.M.

    1980-01-01

    Researchers have purified large quantities of Escherichia coli photoreactivating enzyme to apparent homogeneity and have studied its physical and chemical properties. The enzyme has a molecular weight of 36,800 and a S/sub 20,w/ 0 of 3.72 S. Amino acid analysis revealed an apparent absence of tryptophan, a low content of aromatic residues, and the presence of no unusual amino acids. The N terminus is arginine. The purified enzyme contained up to 13% carbohydrate by weight. The carbohydrate was composed of mannose, galactose, glucose, and N-acetylglucosamine. The enzyme is also associated with RNA containing uracil, adenine, guanine, and cytosine with no unusual bases detected

  6. Multiplex Genome Editing in Escherichia coli

    DEFF Research Database (Denmark)

    Ingemann Jensen, Sheila; Nielsen, Alex Toftgaard

    2018-01-01

    Lambda Red recombineering is an easy and efficient method for generating genetic modifications in Escherichia coli. For gene deletions, lambda Red recombineering is combined with the use of selectable markers, which are removed through the action of, e.g., flippase (Flp) recombinase. This PCR......-based engineering method has also been applied to a number of other bacteria. In this chapter, we describe a recently developed one plasmid-based method as well as the use of a strain with genomically integrated recombineering genes, which significantly speeds up the engineering of strains with multiple genomic...

  7. Expression of maize prolamins in Escherichia Coli

    International Nuclear Information System (INIS)

    Wang, Szu-zhen; Esen, Asim

    1985-01-01

    We have constructed a cDNA expression library of developing corn (Zea manys L.) endosperm using plasmid pUC8 as vector and Escherichia coli strain DH1 as host. The expression library was screened with non-radioactive immunological probes to detect the expression of gamma-zein and alpha-zein. When anti-gamma-zein antibody was used as the probe, 23 colonies gave positive reactions. The lengths of cDNA inserts of the 23 colonies were found to be 250-900 base pairs. When anti-alpha zein antibody was used, however, fewer colonies gave positive reactions. The library was also screened by colony-hybridization with 32 P-labeled DNA probes. Based on immunological and hybridization screening of the library and other evidence, we conclude that alpha-zein was either toxic to E. coli cells or rapidly degraded whereas gamma-zein and its fragments were readily expressed. (author)

  8. Genes under positive selection in Escherichia coli

    DEFF Research Database (Denmark)

    Petersen, Lise; Bollback, Jonathan P; Dimmic, Matt

    2007-01-01

    We used a comparative genomics approach to identify genes that are under positive selection in six strains of Escherichia coli and Shigella flexneri, including five strains that are human pathogens. We find that positive selection targets a wide range of different functions in the E. coli genome......, 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...

  9. Effects of peroxide and catalase on near ultraviolet radiation sensitivity in Escherichia coli strains

    International Nuclear Information System (INIS)

    Coombs, A.M.L.; Moss, S.H.

    1987-01-01

    The role of peroxide and catalase on NUV radiation sensitivity was examined in two repair competent E. coli strains, AB1157 and B/r. Exponential phase B/r is considerably more sensitive to NUV radiation than exponential phase AB1157. However, resistance to 5 mmol dm -3 H 2 O 2 was induced in both AB1157 and B/r by pretreating growing cells with 30 μmol dm -3 H 2 O 2 . Pretreatment also induced resistance to broad-band NUV radiation in these strains. The addition of catalase to the post-irradiation plating medium increased survival to the same extent as that provided by pretreatment with 30 μmol dm -3 H 2 O 2 , in both strains. The NUV radiation sensitivity seen in B/r does not appear to be due to a deficiency in enzymes that scavenge H 2 O 2 , as a catalase deficient mutant, E. coli UM1, is more resistant to NUV radiation than B/r. Also, assays for H 2 O 2 scavenging ability show little difference between AB1157 and B/r in this respect. Two hypotheses are put forward to account for the sensitivity of exponential phase B/r. Whilst it is apparent that peroxides and catalase do have a role in NUV radiation damage, it is clear that other factors also influence survival under certain conditions. (author)

  10. Identifying New Small Proteins in Escherichia coli.

    Science.gov (United States)

    VanOrsdel, Caitlin E; Kelly, John P; Burke, Brittany N; Lein, Christina D; Oufiero, Christopher E; Sanchez, Joseph F; Wimmers, Larry E; Hearn, David J; Abuikhdair, Fatimeh J; Barnhart, Kathryn R; Duley, Michelle L; Ernst, Sarah E G; Kenerson, Briana A; Serafin, Aubrey J; Hemm, Matthew R

    2018-04-12

    The number of small proteins (SPs) encoded in the Escherichia coli genome is unknown, as current bioinformatics and biochemical techniques make short gene and small protein identification challenging. One method of small protein identification involves adding an epitope tag to the 3' end of a short open reading frame (sORF) on the chromosome, with synthesis confirmed by immunoblot assays. In this study, this strategy was used to identify new E. coli small proteins, tagging 80 sORFs in the E. coli genome, and assayed for protein synthesis. The selected sORFs represent diverse sequence characteristics, including degrees of sORF conservation, predicted transmembrane domains, sORF direction with respect to flanking genes, ribosome binding site (RBS) prediction, and ribosome profiling results. Of 80 sORFs, 36 resulted in encoded synthesized proteins-a 45% success rate. Modeling of detected versus non-detected small proteins analysis showed predictions based on RBS prediction, transcription data, and ribosome profiling had statistically-significant correlation with protein synthesis; however, there was no correlation between current sORF annotation and protein synthesis. These results suggest substantial numbers of small proteins remain undiscovered in E. coli, and existing bioinformatics techniques must continue to improve to facilitate identification. © 2018 The Authors. Proteomics Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, Towson University.

  11. Transport proteins promoting Escherichia coli pathogenesis

    Science.gov (United States)

    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

  12. Transport proteins promoting Escherichia coli pathogenesis.

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Effect of gama irradiation (Co60 in the control of Enterococci spp. and Escherichia coli in chilled chicken (Gallus gallus heart

    Directory of Open Access Journals (Sweden)

    Marta Maria Braga Batista Soares Xavier

    2016-09-01

    Full Text Available The present study aimed to evaluate the efficiency of the irradiation process in the control of Enterococci spp. and Escherichia coli in chilled chicken heart samples acquired in an industry located in the West Zone of Rio de Janeiro, Brazil, using irradiation doses of 1.5 kGy, 3, 0 kGy and 4.5 kGy. These microorganisms are related to fecal contamination, and are indicators of the sanitary processing conditions of the foodstuffs. The bacteriological analyses were conducted applying the methodologies and standards recommended by Brazilian norms resolution no. 12 (BRASIL, 2001 and instruction no. 62 (BRASIL, 2003 Regarding Escherichia coli, no statistically significant difference among the four groups (control, 1.5 kGy, 3.0 kGy and 4.5 kGy was observed (p> 0.05. The Most Probable Number (MPN for Enterococci spp. was not proven in the investigated samples. Thus, the Co60 gamma irradiation process was effective in eliminating Escherichia coli, and the lowest dose, of 1.5 kGy, was enough to abolish this enteropathogen from the evaluated samples.

  14. Effects of in-feed Chlortetracycline Prophylaxis of beef cattle on animal health and antimicrobial-resistant Escherichia coli

    Science.gov (United States)

    Objective: The objective of this study was to evaluate the effect of a one-time, five-day in-feed CTC prophylaxis on animal health (morbidity and body weight gain), occurrence of TETr E. coli, and occurrence of 3GCr E. coli over a four-month follow-up period. Experimental Design & Analysis: We eval...

  15. A stochastic killing system for biological containment of Escherichia coli

    DEFF Research Database (Denmark)

    Klemm, P.; Jensen, Lars Bogø; Molin, Søren

    1995-01-01

    Bacteria with a stochastic conditional lethal containment system have been constructed. The invertible switch promoter located upstream of the fimA gene from Escherichia coli was inserted as expression cassette in front of the Lethal gef gene deleted of its own natural promoter. The resulting...... fusion was placed on a plasmid and transformed to E. coli. The phenotype connected with the presence of such a plasmid was to reduce the population growth rate with increasing significance as the cell growth rate was reduced. In very fast growing cells, there was no measurable effect on growth rate. When...

  16. The effects of exogenous catalase on broad-spectrum near-UV (300-400nm) treated Escherichia coli cells

    International Nuclear Information System (INIS)

    Sammartano, L.J.; Tuveson, R.W.

    1984-01-01

    Catalase incorporated into plating medium protects against inactivation and mutagenesis by broad-spectrum near-ultraviolet wavelength (300-400nm) (NUV) radiation in strains of Escherichia coli. Plating medium containing catalase does not provide protection against inactivation by wavelengths in the FUV region. Catalase added to the cell suspension during or added immediately after NUV exposure also protects against inactivation. The protection provided by catalase suggests a possible role for hydrogen peroxide in the processes of inactivation and mutagenesis by broad-spectrum NUV. (author)

  17. Adhesion of Escherichia coli under flow conditions reveals potential novel effects of FimH mutations

    DEFF Research Database (Denmark)

    Feenstra, T.; Schmidt Thøgersen, Mariane; Wieser, E.

    2017-01-01

    H mutations on bacterial adhesion using a novel adhesion assay, which models the physiological flow conditions bacteria are exposed to. We introduced 12 different point mutations in the mannose binding pocket of FimH in an E. coli strain expressing type 1 fimbriae only (MSC95-FimH). We compared the bacterial...... adhesion of each mutant across several commonly used adhesion assays, including agglutination of yeast, adhesion to mono- and tri-mannosylated substrates, and static adhesion to bladder epithelial and endothelial cells. We performed a comparison of these assays to a novel method that we developed to study...... mutations abrogated adhesion. We demonstrated that FimH residues E50 and T53 are crucial for adhesion under flow conditions. The coating of endothelial cells on biochips and modelling of physiological flow conditions enabled us to identify FimH residues crucial for adhesion. These results provide novel...

  18. Effects of peroxide and catalase on near ultraviolet radiation sensitivity in Escherichia coli strains

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, A.M.L.; Moss, S.H.

    1987-03-01

    The role of peroxide and catalase on NUV radiation sensitivity was examined in two repair competent E. coli strains, AB1157 and B/r. Exponential phase B/r is considerably more sensitive to NUV radiation than exponential phase AB1157. However, resistance to 5 mmol dm/sup -3/ H/sub 2/O/sub 2/ was induced in both AB1157 and B/r by pretreating growing cells with 30 ..mu..mol dm/sup -3/ H/sub 2/O/sub 2/. Pretreatment also induced resistance to broad-band NUV radiation in these strains. The addition of catalase to the post-irradiation plating medium increased survival to the same extent as that provided by pretreatment with 30 ..mu..mol dm/sup -3/ H/sub 2/O/sub 2/, in both strains. The NUV radiation sensitivity seen in B/r does not appear to be due to a deficiency in enzymes that scavenge H/sub 2/O/sub 2/, as a catalase deficient mutant, E. coli UM1, is more resistant to NUV radiation than B/r. Also, assays for H/sub 2/O/sub 2/ scavenging ability show little difference between AB1157 and B/r in this respect. Two hypotheses are put forward to account for the sensitivity of exponential phase B/r. Whilst it is apparent that peroxides and catalase do have a role in NUV radiation damage, it is clear that other factors also influence survival under certain conditions.

  19. Combined effect of ultrasound, heat, and pressure on Escherichia coli O157:H7, polyphenol oxidase activity, and anthocyanins in blueberry (Vaccinium corymbosum) juice.

    Science.gov (United States)

    Zhu, Jinyan; Wang, Yuehua; Li, Xinghe; Li, Bin; Liu, Suwen; Chang, Nan; Jie, Ding; Ning, Chong; Gao, Haiyan; Meng, Xianjun

    2017-07-01

    The objective of this study was to evaluate the effect of different treatments-heat treatment (HT), sonication (SC), thermosonication (TS), manosonication (MS), manothermal (MT), and manothermosonication (MTS) on Escherichia coli O157:H7, polyphenol oxidase (PPO), and anthocyanin content in blueberry juice. First, samples were treated at different temperatures (30, 40, 50, 60, 70, and 80°C) and power intensities (280, 420, 560, and 700W) for 10min. Subsequently, samples were treated using combinations of power intensity and mild temperature for 10min. For further study, samples were treated using HT (80°C), TS (40°C, 560W), MT (350MPa, 40°C), MS (560W, 5min/350MPa), or MTS (560W, 5min, 40°C/350MPa, 40°C) for 5, 10, 15, 20min for each treatment, and the results compared between treatments. HT significantly reduced PPO activation (2.05% residual activity after only 5min), and resulted in a 2.00-log reduction in E. coli O157:H7 and an 85.25% retention of anthocyanin. Escherichia coli O157:H7 was slightly inactivated by TS after 5min (0.17-log reduction), while residual PPO activity was 23.36% and anthocyanin retention was 98.48%. However, Escherichia coli O157:H7 was rapidly inactivated by MTS (5.85-log reduction) after 5min, while anthocyanin retention was 97.49% and residual PPO activity dropped to 10.91%. The destruction of E. coli cells as a result of these treatments were confirmed using SEM and TEM. Therefore, a combination of sonication, high pressure, and mild heat allows the safety of blueberry juice to be maintained without compromising the retention of desirable antioxidant compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Genetically Engineered Escherichia coli Nissle 1917 Synbiotics Reduce Metabolic Effects Induced by Chronic Consumption of Dietary Fructose.

    Directory of Open Access Journals (Sweden)

    Chaudhari Archana Somabhai

    Full Text Available To assess protective efficacy of genetically modified Escherichia coli Nissle 1917 (EcN on metabolic effects induced by chronic consumption of dietary fructose.EcN was genetically modified with fructose dehydrogenase (fdh gene for conversion of fructose to 5-keto-D-fructose and mannitol-2-dehydrogenase (mtlK gene for conversion to mannitol, a prebiotic. Charles foster rats weighing 150-200 g were fed with 20% fructose in drinking water for two months. Probiotic treatment of EcN (pqq, EcN (pqq-glf-mtlK, EcN (pqq-fdh was given once per week 109 cells for two months. Furthermore, blood and liver parameters for oxidative stress, dyslipidemia and hyperglycemia were estimated. Fecal samples were collected to determine the production of short chain fatty acids and pyrroloquinoline quinone (PQQ production.EcN (pqq-glf-mtlK, EcN (pqq-fdh transformants were confirmed by restriction digestion and functionality was checked by PQQ estimation and HPLC analysis. There was significant increase in body weight, serum glucose, liver injury markers, lipid profile in serum and liver, and decrease in antioxidant enzyme activity in high-fructose-fed rats. However the rats treated with EcN (pqq-glf-mtlK and EcN (pqq-fdh showed significant reduction in lipid peroxidation along with increase in serum and hepatic antioxidant enzyme activities. Restoration of liver injury marker enzymes was also seen. Increase in short chain fatty acids (SCFA demonstrated the prebiotic effects of mannitol and gluconic acid.Our study demonstrated the effectiveness of probiotic EcN producing PQQ and fructose metabolizing enzymes against the fructose induced hepatic steatosis suggesting that its potential for use in treating fructose induced metabolic syndrome.

  1. Ribosome slowed by mutation to streptomycin resistance. [Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Galas, D J; Branscomb, E W

    1976-08-12

    The effect of mutation to streptomycin resistance on the speed of polypeptide elongation in Escherichia coli was investigated. Translation speed was determined by measuring the time required for the first newly synthesized ..beta..-galactosidase molecules to appear after induction of the lactose operon. The results showed that ribosome speed is not a fixed parameter inherent to the protein synthetic apparatus, but a variable determined by the kinetics of translation and ultimately by the structure of the ribosome. (HLW)

  2. Efecto citotóxico en colon humano de Escherichia coli enterohemorrágico aislado de terneros con diarrea sanguinolenta Cytotoxic effect in human colon of enterohemorrhagic Escherichia coli isolated from calves with bloody diarrhea

    Directory of Open Access Journals (Sweden)

    V. Pistone Creydt

    2005-09-01

    Full Text Available Escherichia coli productor de toxina Shiga (STEC es el patógeno emergente en alimentos de mayor impacto, siendo su principal reservorio el ganado bovino. STEC puede causar diarrea, colitis hemorrágica y síndrome urémico hemolítico. El presente trabajo estudió la acción citotóxica de dos cepas de STEC aisladas de heces de terneros diarreicos en colon humano in vitro. Los fragmentos se montaron como un diafragma en una cámara de Ussing y se incubaron con las cepas patógenas. El flujo neto absortivo de agua (Jw disminuyó y la corriente de cortocircuito (Isc aumentó significativamente (P Shiga toxin-producing E. coli (STEC is one of the most important emergent pathogen in foods, being its main reservoir bovine cattle. STEC can cause diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome. The present work have studied the cytotoxic action in human colon of cultures of two STEC strains isolated from faeces of calves with bloody diarrhea. Colonic mucosa was mounted as a diaphragm in a Ussing chamber and incubated with the cultures of pathogenic strains. Net water flow (Jw decreased and the short-circuit current (Isc increased significantly (p < 0,01 compared to negative control. Tissues showed an erosion of the mucose, epithelial exfoliation, and presence of pseudo-membranes in the lumen. Mild circulatory lesions were observed in the lamina propia. A moderate neutrophils infiltration was observed in the lumen and into the epithelial cells. Colonic crypts were not disrupted. Both experimental strains caused a similar lesion on colon tissues. This is the first study that shows that cultures of STEC strains isolated from bovine cattle produce cytotoxic effects in vitro in human colon.

  3. Antibiotic resistant Salmonella and Escherichia coli isolated from ...

    African Journals Online (AJOL)

    Results: A hundred and four indigenous chicken rectal swabs were analysed, of which 67.3% were contaminated with Escherichia coli and 12.5% with Salmonella typhimurium. Seventy Escherichia coli isolates showed resistance phenotypes to one, two or more antibiotics. The most common antimicrobial resistance pattern ...

  4. Chromatin architecture and gene expression in Escherichia coli

    DEFF Research Database (Denmark)

    Willenbrock, Hanni; Ussery, David

    2004-01-01

    Two recent genome-scale analyses underscore the importance of DNA topology and chromatin structure in regulating transcription in Escherichia coli.......Two recent genome-scale analyses underscore the importance of DNA topology and chromatin structure in regulating transcription in Escherichia coli....

  5. Escherichia coli clearance after splenic autotransplants

    International Nuclear Information System (INIS)

    Marques, R.G.; Petroianu, A.; Oliveira, M.B.N.; Bernardo-Filho, M.; Portela, M.C.

    2002-01-01

    Background: Splenic autotransplantation seems to be the only alternative for preservation of splenic tissue, after total splenectomy. The present study was carried out to analyze Escherichia coli depuration by mononuclear phagocyte system organs after total splenectomy and splenic autotransplantation. Methods: We utilized an experimental model including young and adult Wistar rats, of both sexes, submitted to total splenectomy and splenic autotransplantation. The evaluation method was intravenous inoculation of a suspension of Escherichia coli labeled with technetium-99m. We analyzed bacteria uptake by mononuclear phagocyte system organs and bacteria remnant in the bloodstream. Results: There was no difference between young and adult animals in bacteria uptake by mononuclear phagocyte system organs. In the comparison of groups, it was found out that the mean percent uptake by spleen and liver of animals in the control group was higher than that observed for animals with splenic implants. However, bacteria uptake in the lung was higher in the splenic implant group than in the control group. Although spleen bacteria uptake in the control group animals has been higher than that of animals in the splenic implant group, the remnant bacteria in the bloodstream was similar. Animals submitted to isolated total splenectomy showed higher bacteria remnant in the bloodstream than animals of the control group or the group submitted to total splenectomy combined with splenic autotransplantation. Conclusion: Our results indicate that autogenous splenic implant is efficacious in bacteria depuration in rats, by means of their macrophages phagocytosis. In addition, it does not modify bacteria removal function of liver and lung

  6. Synthesis of avenanthramides using engineered Escherichia coli.

    Science.gov (United States)

    Lee, Su Jin; Sim, Geun Young; Kang, Hyunook; Yeo, Won Seok; Kim, Bong-Gyu; Ahn, Joong-Hoon

    2018-03-22

    Hydroxycinnamoyl anthranilates, also known as avenanthramides (avns), are a group of phenolic alkaloids with anti-inflammatory, antioxidant, anti-itch, anti-irritant, and antiatherogenic activities. Some avenanthramides (avn A-H and avn K) are conjugates of hydroxycinnamic acids (HC), including p-coumaric acid, caffeic acid, and ferulic acid, and anthranilate derivatives, including anthranilate, 4-hydroxyanthranilate, and 5-hydroxyanthranilate. Avns are primarily found in oat grain, in which they were originally designated as phytoalexins. Knowledge of the avns biosynthesis pathway has now made it possible to synthesize avns through a genetic engineering strategy, which would help to further elucidate their properties and exploit their beneficial biological activities. The aim of the present study was to synthesize natural avns in Escherichia coli to serve as a valuable resource. We synthesized nine avns in E. coli. We first synthesized avn D from glucose in E. coli harboring tyrosine ammonia lyase (TAL), 4-coumarate:coenzyme A ligase (4CL), anthranilate N-hydroxycinnamoyl/benzoyltransferase (HCBT), and anthranilate synthase (trpEG). A trpD deletion mutant was used to increase the amount of anthranilate in E. coli. After optimizing the incubation temperature and cell density, approximately 317.2 mg/L of avn D was synthesized. Avn E and avn F were then synthesized from avn D, using either E. coli harboring HpaBC and SOMT9 or E. coli harboring HapBC alone, respectively. Avn A and avn G were synthesized by feeding 5-hydroxyanthranilate or 4-hydroxyanthranilate to E. coli harboring TAL, 4CL, and HCBT. Avn B, avn C, avn H, and avn K were synthesized from avn A or avn G, using the same approach employed for the synthesis of avn E and avn F from avn D. Using different HCs, nine avns were synthesized, three of which (avn D, avn E, and avn F) were synthesized from glucose in E. coli. These diverse avns provide a strategy to synthesize both natural and unnatural avns

  7. Effects of Space Flight, Clinorotation, and Centrifugation on the Growth and Metabolism of Escherichia Coli

    Science.gov (United States)

    Brown, Robert B.

    1999-01-01

    Previous experiments have shown that space flight stimulates bacterial growth and metabolism. An explanation for these results is proposed, which may eventually lead to improved terrestrial pharmaceutical production efficiency. It is hypothesized that inertial acceleration affects bacterial growth and metabolism by altering the transport phenomena in the cells external fluid environment. It is believed that this occurs indirectly through changes in the sedimentation rate acting on the bacteria and buoyancy-driven convection acting on their excreted by-products. Experiments over a broad range of accelerations consistently supported this theory. Experiments at I g indicated that higher concentrations of excreted by products surrounding bacterial cells result in a shorter lag phase. Nineteen additional experiments simulated 0 g and 0.5 g using a clinostat, and achieved 50 g, 180 g, and 400 g using a centrifuge. These experiments showed that final cell density is inversely related to the level of acceleration. The experiments also consistently showed that acceleration affects the length of the lag phase in a non-monotonic, yet predictable, manner. Additional data indicated that E. coli metabolize glucose less efficiently at hypergravity, and more efficiently at hypogravity. A space-flight experiment was also performed. Samples on orbit had a statistically significant higher final cell density and more efficient metabolism than did ground controls. These results. which were similar to simulations of 0 g using a clinostat, support the theory that gravity only affects bacterial growth and metabolism indirectly, through changes in the bacteria's fluid environment.

  8. DNA turnover in buffer-held Escherichia coli and its effect on repair of UV damage

    International Nuclear Information System (INIS)

    Tang, M.S.; Wang, T.C.V.; Patrick, M.H.

    1979-01-01

    Continuous DNA degradation and resynthesis, without a net change in cellular DNA content, were observed in buffer-held, non-irradiated E. coli B/r. This constant DNA turnover probably involves most of the genome and reflects random sites of DNA repair due to the polA-dependent excision-resynthesis repair pathway. Under these non-growth conditions it appears that at any given time there is a minimum of one repair site per 6.5 x 10 6 daltons DNA, each of which is at least 160 nucleotides long. While the amount of DNA degradation is not influenced by prior exposure to UV radiation, the synthetic activity decreases with increasing UV fluence. It is suggested that when sites of DNA turnover occur opposite to cyclobutyl dipyrimidines in UV-irradiated cells, repair of the latter damage can be prevented. This implies that both beneficial and deleterious processes take place in irradiated buffer-held cells, and that cell survival depends on the delicate balance between DNA turnover and repair of UV-damage. Based on these findings, a model is proposed to explain the limit repair observed during post-irradiation liquid-holding and to account for the large difference in cell survival between irradiation at low fluence rates (fluence-rate dependent recovery) and at high fluence rates followed by liquid-holding (liquid-holding recovery). (author)

  9. Effect of storage temperaturas on growth and survival of Escherichia coli 0157: H7 inoculated in foods from a neotropical environment

    Directory of Open Access Journals (Sweden)

    María Laura Arias

    2001-06-01

    Full Text Available Escherichia coli 0157: H7 has emerged as a new pathogen and is found worldwide. We studied the effect of several storage temperatures on the survival of this bacterium in common foods from a neotropical environment (Costa Rica because at least seven clinical cases have been reported from the country, and no epidemiological link or probable food association has been described. High (106- 108 CFU/ml and low (104-106 CFU/ml populations of E. coli were inoculated (three replications in ground meat, chopped cabbage, chicken giblets and pasteurized milk and incubated at 0, 6 and 12 °C for 24, 48 and 72 h. Vegetables and milk were also stored at 22 °C for the sarne periods.The E. coli 0157: H7 enumeration was done according to the methodology describes in the Bacteriological Analytical Manual. Populations of E. coli 0157: H7 showed either an increasing or decreasing trend, according to temperature, time or food base. Our data indicate that E. coli 0157: H7 is capable of surviving and growing in meat, cabbage, milk and chicken giblets; food items commonly consunied by Costa Ricans.Escherichia coli 0157, H7 ha emergido como un nuevo patógeno y se encuentra mundialmente. En Costa Rica, por lo menos ha informado de siete casos clínicos, y no se ha encontrado un lazo epidemiológico o asociación con alimentos. El propósito de este estudio fue determinar el efecto de diferentes temperaturas de almacenamiento sobre la sobrevivencia de esta bacteria en alimentos de uso común. Una población alta de E. Coli (106- 108 UFC/ml y una baja (104-106 UFC/ml fueron inoculadas (tres réplicas en carne picada, repollo picado, vísceras de pollo y leche pasteurizada e incubadas a 0, 6 y 1 °C por 24, 48 y 72 h. Los vegetales y la leche también fueron incubados a 22 °C por los mismos períodos. La enumeración de E. Coli 0157: H7 se realizó de acuerdo a la metodología descrita en el Bacteriological Analytical Manual. Las poblaciones de E. coli mostraron

  10. ANTIBACTERIAL EFFECT OF GARLIC (ALLIUM SATIVUM AND GINGER (ZINGIBER OFFICINALE AGAINST STAPHYLOCOCCUS AUREUS, SALMONELLA TYPHI, ESCHERICHIA COLI AND BACILLUS CEREUS

    Directory of Open Access Journals (Sweden)

    Bandna Chand

    2013-02-01

    Full Text Available Antibacterial activity of extracts of Allium sativum (garlic and Zingiber officinale (ginger has been evaluated against four different bacteria namely Escherichia coli, Salmonella Typhi, Staphylococcus aureus and Bacillus cereus. Two methods were used to determine the antimicrobial activity of garlic and ginger extracts namely disk diffusion method and agar well diffusion method. Garlic extract exhibited excellent antibacterial activity against all four test organisms while ginger extract showed antibacterial activity against Bacillus cereus and Staphylococcus aureus only. In addition, agar well diffusion method showed higher zone in inhibition when compared with the zone of inhibition produced by the spice of same concentration against the test microorganism by disk diffusion method. Antibiotic sensitivity of the four different bacteria was tested with commercially available antibiotics namely Ciprofloxacin; Oxytetracycline; Vancomycin; Streptomycin; Gentamicin; Tetracycline; Novobiocin; Amikacin and Penicillin G. Penicillin G produced the highest zone of inhibition of 40.00±0.00against Staphylococcus aureus and the lowest zone of inhibition of 0.00±0.00against Escherichia coli.

  11. Antibacterial effects of Apis mellifera and stingless bees honeys on susceptible and resistant strains of Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae in Gondar, Northwest Ethiopia.

    Science.gov (United States)

    Ewnetu, Yalemwork; Lemma, Wossenseged; Birhane, Nega

    2013-10-19

    Honey is a natural substance produced by honeybees and has nutritional and therapeutic uses. In Ethiopia, honeys are used traditionally to treat wounds, respiratory infections and diarrhoea. Recent increase of drug resistant bacteria against the existing antibiotics forced investigators to search for alternative natural remedies and evaluate their potential use on scientific bases. Thus, the aim of this study was to evaluate the antibacterial effects of different types of honeys in Ethiopia which are used traditionally to treat different types of respiratory and gastrointestinal infections. Mueller Hinton agar (70191) diffusion and nutrient broth culture medium assays were performed to determine susceptibility of Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922) and resistant clinical isolates (Methicillin resistant Staphylococcus aureus(MRSA), Escherichia coli(R) and Klebsiella pneumoniae (R), using honeys of Apis mellifera and stingless bees in northern and north western Ethiopia. Honey of the stingless bees produced the highest mean inhibition (22.27 ± 3.79 mm) compared to white honey (21.0 ± 2.7 mm) and yellow honey (18.0 ± 2.3 mm) at 50% (v/v) concentration on all the standard and resistant strains. Stingless bees honey was found to have Minimum Inhibitory Concentration (MIC) of 6.25% (6.25 mg/ml) for 80% of the test organisms compared to 40% for white and yellow Apis mellifera honeys. All the honeys were found to have minimum bactericidal concentration (MBC) of 12.5% (12.5 mg/ml) against all the test organisms. Staphylococcus aureus (ATCC 25923) was susceptible to amoxicillin, methicillin, kanamycine, tetracycline, and vancomycine standard antibiotic discs used for susceptibility tests. Similarly, Escherichia coli (ATCC 25922) was found susceptible for kanamycine, tetracycline and vancomycine. Escherichia coli (ATCC 25922) has not been tested for amoxicillin ampicillin and methicillin. The susceptibility tests performed against

  12. A ΔdinB mutation that sensitizes Escherichia coli to the lethal effects of UV- and X-radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Mei-Chong W.; Franco, Magdalena; Vargas, Doris M. [Department of Biological Sciences, San Jose State University, San Jose, CA 95192 (United States); Hudman, Deborah A. [Department of Microbiology and Immunology, A.T. Still University, Kirksville College of Osteopathic Medicine, Kirksville, MO 63501 (United States); White, Steven J. [Department of Biological Sciences, San Jose State University, San Jose, CA 95192 (United States); Fowler, Robert G., E-mail: rfowler@sjsu.edu [Department of Biological Sciences, San Jose State University, San Jose, CA 95192 (United States); Sargentini, Neil J. [Department of Microbiology and Immunology, A.T. Still University, Kirksville College of Osteopathic Medicine, Kirksville, MO 63501 (United States)

    2014-05-15

    Highlights: • We describe Δ(dinB-yafN)883(::kan), a novel dinB allele, referred to as ΔdinB883, a deletion that sensitizes E. coli cells to UV irradiation. • This UV radiation sensitivity is most acute in the early logarithmic phase of culture growth. • This UV radiation sensitivity is completely dependent upon a functional umuDC operon. • Sequencing reveals ΔdinB883 retains the proximal 161 nucleotides, i.e., 54 amino acids, of the wild-type sequence. • The ΔdinB883 mutant is hypothesized to produce a peptide of 83 amino acids, DinB883, that compromises UmuDC function. - Abstract: The DinB (PolIV) protein of Escherichia coli participates in several cellular functions. We investigated a dinB mutation, Δ(dinB-yafN)883(::kan) [referred to as ΔdinB883], which strongly sensitized E. coli cells to both UV- and X-radiation killing. Earlier reports indicated dinB mutations had no obvious effect on UV radiation sensitivity which we confirmed by showing that normal UV radiation sensitivity is conferred by the ΔdinB749 allele. Compared to a wild-type strain, the ΔdinB883 mutant was most sensitive (160-fold) in early to mid-logarithmic growth phase and much less sensitive (twofold) in late log or stationary phases, thus showing a growth phase-dependence for UV radiation sensitivity. This sensitizing effect of ΔdinB883 is assumed to be completely dependent upon the presence of UmuDC protein; since the ΔdinB883 mutation did not sensitize the ΔumuDC strain to UV radiation killing throughout log phase and early stationary phase growth. The DNA damage checkpoint activity of UmuDC was clearly affected by ΔdinB883 as shown by testing a umuC104 ΔdinB883 double-mutant. The sensitivities of the ΔumuDC strain and the ΔdinB883 ΔumuDC double-mutant strain were significantly greater than for the ΔdinB883 strain, suggesting that the ΔdinB883 allele only partially suppresses UmuDC activity. The ΔdinB883 mutation partially sensitized (fivefold) uvrA and uvr

  13. Multiple loci affecting photoreactivation in Escherichia coli

    International Nuclear Information System (INIS)

    Sutherland, B.M.; Hausrath, S.G.

    1979-01-01

    Sutherland et al. mapped a phr gene in Escherichia coli at 17 min and found that induction of an E. coli stain lysogenic for a lambda phage carrying this gene increased photoreactivating enzyme levels 2,000-fold. Recently, Smith and Youngs and Sancar and Rupert located a phr gene at 15.9 min. We have therefore investigated the properties of photoreactivating enzyme and cellular photoreactivation in cells containing deletions of the gene at 17 min. Cells with this deletion photoreactivated ultraviolet-induced killing at a rate 20% of normal; they also contained approximately 20% of the normal photoreactivating enzyme level. The residual enzyme in these cells was characterized to determine whether the reduced cellular photoreactivation rate and photoreactivating enzyme levels resulted from reduced numbers of normal enzymes or from an altered enzyme. Photoreactivating enzymes from strains carrying a deletion of the region at 17 min has an apparent K/sub m/ about two- to threefold higher than normal enzyme and showed markedly increased heat lability. The gene at 17 min thus contains information determining the function of the E. coli photoreactivating enzyme rather than the quantity of the enzyme. It is proposed that the gene at 17 min be termed phrA and that located at 15.9 min be termed phrB

  14. Variant innate immune responses of mammary epithelial cells to challenge by Staphylococcus aureus, Escherichia coli and the regulating effect of taurine on these bioprocesses.

    Science.gov (United States)

    Zheng, Liuhai; Xu, Yuanyuan; Lu, Jinye; Liu, Ming; Bin Dai; Miao, Jinfeng; Yin, Yulong

    2016-07-01

    Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are important pathogens causing subclinical and clinical bovine mastitis, respectively. Taurine, an organic acid found in animal tissues, has been used for the treatment of various superficial infections and chronic inflammations. We challenged a bovine mammary epithelial cell (MEC) line (MAC-T) or a mouse mammary epithelial cell line (EpH4-Ev) with either E. coli or S. aureus and compared the responses of MECs to these 2 pathogens. We also examined the regulatory effects of taurine on these responses. Receptor analyses showed that both TLR2 and TLR4 are upregulated upon exposure to either E. coli or S. aureus. Taurine pre-treatment dampened upregulation to some extent. E. coli and S. aureus stimulated comparable levels of ROS, which could be inhibited by taurine pre-treatment. E. coli infection elicited a dramatic change in iNOS expression. Taurine significantly decreased iNOS expression in the S. aureus challenged group. Protein microarray demonstrated that 32/40 and 8/40 inflammatory molecules/mediators were increased after E. coli or S. aureus challenge, respectively. The fold changes of most molecules were higher in the E. coli infection group than that in the S. aureus infection group. Taurine negatively regulated the inflammatory profile in both bacterial infections. Pro-inflammatory cytokines (such as TNF-α) connected with TLR activation were down-regulated by taurine pre-treatment. The influence of TAK-242 and OxPAPC on cytokine/molecule expression profiles to E. coli challenge are different than to S. aureus. Some important factors (MyD88, TNF-α, IL-1β, iNOS and IL-6) mediated by TLR activation were suppressed either in protein microarray or special assay (PCR/kits) or both. TAK-242 restrained ROS production and NAGase activity similar to the effect of taurine in E. coli challenge groups. The detection of 3 indices (T-AOC, SOD and MDA) reflecting oxidative stress in vivo, showed that

  15. Effects of household washing on bacterial load and removal of Escherichia coli from lettuce and "ready-to-eat" salads.

    Science.gov (United States)

    Uhlig, Elisabeth; Olsson, Crister; He, Jiayi; Stark, Therese; Sadowska, Zuzanna; Molin, Göran; Ahrné, Siv; Alsanius, Beatrix; Håkansson, Åsa

    2017-11-01

    Customer demands for fresh salads are increasing, but leafy green vegetables have also been linked to food-borne illness due to pathogens such as Escherichia coli O157:H7. As a safety measure, consumers often wash leafy vegetables in water before consumption. In this study, we analyzed the efficiency of household washing to reduce the bacterial content. Romaine lettuce and ready-to-eat mixed salad were washed several times in flowing water at different rates and by immersing the leaves in water. Lettuce was also inoculated with E. coli before washing. Only washing in a high flow rate (8 L/min) resulted in statistically significant reductions ( p  < .05), "Total aerobic count" was reduced by 80%, and Enterobacteriaceae count was reduced by 68% after the first rinse. The number of contaminating E. coli was not significantly reduced. The dominating part of the culturable microbiota of the washed lettuce was identified by rRNA 16S sequencing of randomly picked colonies. The majority belonged to Pseudomonadaceae , but isolates from Enterobacteriaceae and Staphylococcaceaceae were also frequently found. This study shows the inefficiency of tap water washing methods available for the consumer when it comes to removal of bacteria from lettuce. Even after washing, the lettuce contained high levels of bacteria that in a high dose and under certain circumstances may constitute a health risk.

  16. Effects of the deletion of the Escherichia coli frataxin homologue CyaY on the respiratory NADH:ubiquinone oxidoreductase

    Directory of Open Access Journals (Sweden)

    Grauman Peter L

    2007-07-01

    Full Text Available Abstract Background Frataxin is discussed as involved in the biogenesis of iron-sulfur clusters. Recently it was discovered that a frataxin homologue is a structural component of the respiratory NADH:ubiquinone oxidoreductase (complex I in Thermus thermophilus. It was not clear whether frataxin is in general a component of complex I from bacteria. The Escherichia coli homologue of frataxin is coined CyaY. Results We report that complex I is completely assembled to a stable and active enzyme complex equipped with all known iron-sulfur clusters in a cyaY mutant of E. coli. However, the amount of complex I is reduced by one third compared to the parental strain. Western blot analysis and live cell imaging of CyaY engineered with a GFP demonstrated that CyaY is located in the cytoplasm and not attached to the membrane as to be expected if it were a component of complex I. Conclusion CyaY plays a non-essential role in the assembly of complex I in E. coli. It is not a structural component but may transiently interact with the complex.

  17. Effects of Cover Crop Species and Season on Population Dynamics of Escherichia coli and Listeria innocua in Soil.

    Science.gov (United States)

    Reed-Jones, Neiunna L; Marine, Sasha Cahn; Everts, Kathryne L; Micallef, Shirley A

    2016-01-04

    Cover crops provide several ecosystem services, but their impact on enteric bacterial survival remains unexplored. The influence of cover cropping on foodborne pathogen indicator bacteria was assessed in five cover crop/green manure systems: cereal rye, hairy vetch, crimson clover, hairy vetch-rye and crimson clover-rye mixtures, and bare ground. Cover crop plots were inoculated with Escherichia coli and Listeria innocua in the fall of 2013 and 2014 and tilled into the soil in the spring to form green manure. Soil samples were collected and the bacteria enumerated. Time was a factor for all bacterial populations studied in all fields (P cover crop was a factor for E. coli in year 1 (P = 0.004) and for L. innocua in year 2 (P = 0.011). In year 1, E. coli levels were highest in the rye and hairy vetch-rye plots. In year 2, L. innocua levels were higher in hairy vetch-rye (P = 0.01) and hairy vetch (P = 0.03) plots than in the rye plot. Bacterial populations grew (P cover crops/green manures on bacterial population dynamics in soil varied, being influenced by bacterial species, time from inoculation, soil temperature, rainfall, and tillage; this reveals the need for long-term studies. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  18. Increased multi-drug resistant Escherichia coli from hospitals in ...

    African Journals Online (AJOL)

    Background: Multidrug-resistant Escherichia coli (MDR E. coli) has become a major public health concern in Sudan and many countries, causing failure in treatment with consequent huge health burden. Objectives: To determine the prevalence and susceptibility of MDR E. coli isolated from patients in hospitals at Khartoum ...

  19. Isolation and genomic characterization of Escherichia coli O157:NM ...

    African Journals Online (AJOL)

    Human diseases caused by Escherichia coli O157:NM and E. coli O157:H7 strains have been reported throughout the world. In developed countries, serotype O157:H7 represents the major cause of human diseases; however, there have been increasing reports of non-O157 Shiga toxin (Stx)-producing E. coli strains ...

  20. Neonatal infections caused by Escherichia coli at the National ...

    African Journals Online (AJOL)

    Background: Escherichia coli (E.coli) has been implicated as a common cause of both early and late onset neonatal infections. The emergence of different strains of E.coli that are multiply resistant to commonly used antibiotics has made continuous antibiotics surveillance relevant. Knowledge about common infections ...

  1. neonatal infections caused by escherichia coli at the national

    African Journals Online (AJOL)

    boaz

    Background: Escherichia coli (E.coli) has been implicated as a common cause of both early and late onset neonatal infections. The emergence of different strains of E.coli that are multiply resistant to commonly used antibiotics has made continuous antibiotics surveillance relevant. Knowledge about common infections ...

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

    OpenAIRE

    Reyes, Daniel; Vilchez, Samuel; Paniagua, Margarita; Colque-Navarro, Patricia; Weintraub, Andrej; Möllby, Roland; Kühn, Inger

    2010-01-01

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

  3. Transport of Escherichia coli phage through saturated porous media considering managed aquifer recharge.

    Science.gov (United States)

    Zhang, Wenjing; Li, Shuo; Wang, Shuang; Lei, Liancheng; Yu, Xipeng; Ma, Tianyi

    2018-03-01

    Virus is one of the most potentially harmful microorganisms in groundwater. In this paper, the effects of hydrodynamic and hydrogeochemical conditions on the transportation of the colloidal virus considering managed aquifer recharge were systematically investigated. Escherichia coli phage, vB_EcoM-ep3, has a broad host range and was able to lyse pathogenic Escherichia coli. Bacteriophage with low risk to infect human has been found extensively in the groundwater environment, so it is considered as a representative model of groundwater viruses. Laboratory studies were carried out to analyze the transport of the Escherichia coli phage under varying conditions of pH, ionic strength, cation valence, flow rate, porous media, and phosphate buffer concentration. The results indicated that decreasing the pH will increase the adsorption of Escherichia coli phage. Increasing the ionic strength, either Na + or Ca 2+ , will form negative condition for the migration of Escherichia coli phage. A comparison of different cation valence tests indicated that changes in transport and deposition were more pronounced with divalent Ca 2+ than monovalent Na + . As the flow rate increases, the release of Escherichia coli phage increases and the retention of Escherichia coli phage in the aquifer medium reduces. Changes in porous media had a significant effect on Escherichia coli phage migration. With increase of phosphate buffer concentration, the suspension stability and migration ability of Escherichia coli phage are both increased. Based on laboratory-scale column experiments, a one-dimensional transport model was established to quantitatively describe the virus transport in saturated porous medium.

  4. Bactericidal effect of starch-stabilized zero-valent iron nanoparticles on Escherichia coli

    Directory of Open Access Journals (Sweden)

    Mohammad Mosaferi

    2016-01-01

    Conclusion: The present study showed that nonstabilized Fe 0 nanoparticles have higher bactericidal efficiency than that of S-NZVI. This investigation also suggests that NZVI can be used as an effective and strong agent for antimicrobial applications.

  5. Control of Ribosome Synthesis in Escherichia coli

    DEFF Research Database (Denmark)

    Molin, Søren; Meyenburg, K. von; Måløe, O.

    1977-01-01

    The rate of ribosome synthesis and accumulation in Escherichia coli during the transition after an energy source shift-down was analyzed. The shift was imposed on cultures of stringent and relaxed strains growing in glucose minimal medium by the addition of the glucose analogue {alpha...... and to estimate the transcription time for the rRNA operon under different conditions. In steady states of growth with growth rates ranging from 0.75 to 2.3 doublings/h, as well as during the transition after a shift-down, the transcription time of the rRNA operon was constant. The rate of synthesis of r......RNA correlated during this transition – in contrast to the rate of accumulation (M. T. Hansen et al., J. Bacteriol. 122: 585-591, 1975) – with the ppGpp pool in the same way as has been observed during partial amino acid starvation....

  6. Repair replication in permeabilized Escherichia coli

    International Nuclear Information System (INIS)

    Masker, W.E.; Simon, T.J.; Hanawalt, P.C.

    1975-01-01

    We have examined the modes of DNA synthesis in Escherichia coli strains made permeable to nucleoside triphosphates by treatment with toluene. In this quasi in vitro system, polymerase-I-deficient mutants exhibit a nonconservative mode of synthesis with properties expected for the resynthesis step of excision-repair. This uv-stimulated DNA synthesis can be performed by either DNA polymerase II or III and it also requires the uvrA gene product. It requires the four deoxynucleoside triphosphates; but, in contrast to the semiconservative mode, the ATP requirement can be partially satisfied by other nucleoside triphosphates. The ATP-dependent recBC nuclease is not involved. The observed uv-stimulated mode of DNA synthesis may be part of an alternate excision-repair mechanism which supplements or complements DNA-polymerase-I-dependent repair in vivo

  7. Progressive segregation of the Escherichia coli chromosome

    DEFF Research Database (Denmark)

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

    2006-01-01

    We have followed the fate of 14 different loci around the Escherichia coli chromosome in living cells at slow growth rate using a highly efficient labelling system and automated measurements. Loci are segregated as they are replicated, but with a marked delay. Most markers segregate in a smooth...... temporal progression from origin to terminus. Thus, the overall pattern is one of continuous segregation during replication and is not consistent with recently published models invoking extensive sister chromosome cohesion followed by simultaneous segregation of the bulk of the chromosome. The terminus......, and a region immediately clockwise from the origin, are exceptions to the overall pattern and are subjected to a more extensive delay prior to segregation. The origin region and nearby loci are replicated and segregated from the cell centre, later markers from the various positions where they lie...

  8. Isolation, genotyping, and antimicrobial resistance of zoonotic shiga toxin-producing escherichia coli

    Science.gov (United States)

    Shiga toxin-producing Escherichia coli (STEC) is an enteric pathogen linked to outbreaks of human gastroenteritis with diverse clinical spectra. Traditional culture and isolation methods, including selective enrichment and differential plating, have enabled the effective recovery of STEC. Ruminants ...

  9. Effect of continuous ohmic heating to inactivate Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in orange juice and tomato juice.

    Science.gov (United States)

    Lee, S-Y; Sagong, H-G; Ryu, S; Kang, D-H

    2012-04-01

    The purpose of this study was to investigate the efficacy of continuous ohmic heating for reducing Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in orange juice and tomato juice. Orange juice and tomato juice were treated with electric field strengths in the range of 25-40 V cm(-1) for different treatment times. The temperature of the samples increased with increasing treatment time and electric field strength. The rate of temperature change for tomato juice was higher than for orange juice at all voltage gradients applied. Higher electric field strength or longer treatment time resulted in a greater reduction of pathogens. Escherichia coli O157:H7 was reduced by more than 5 log after 60-, 90- and 180-s treatments in orange juice with 40, 35 and 30 V cm(-1) electric field strength, respectively. In tomato juice, treatment with 25 V cm(-1) for 30 s was sufficient to achieve a 5-log reduction in E. coli O157:H7. Similar results were observed in Salm. Typhimurium and L. monocytogenes. The concentration of vitamin C in continuous ohmic heated juice was significantly higher than in conventionally heated juice (P pasteurize fruit and vegetable juices in a short operating time and that the effect of inactivation depends on applied electric field strengths, treatment time and electric conductivity. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

  10. Evaluation of Colicin Effect on the Induction of Treated Mice in Prevention of Infection Caused by Escherichia coli K99

    Directory of Open Access Journals (Sweden)

    Yahya Tahamtan

    2016-11-01

    Full Text Available Background. Colicin produce by colicinogenic E. coli (CEC arenarrow limited spectrum antimicrobial agents that are able to kill or prevent close related strains. Objective. The objective of this study was to evaluation effect of Colicin to induce immunized mice to prevent infection caused by E. coliK99. Patient and Methods. The experiment was conducted into two mice groups (30 in each group with two weeks old. All mice were administered by streptomycin sulfate prior to treatment to eliminate resident E. coli. Group one was orally inoculated with PBS as control and the second was immunized by Colicin solution as immunize group. Both control and immunized group were challenged by 3 LD 50 of E. coli K99 and follow a week. Results. Immunized mice group were not showed severe clinical signs. While diarrhea with different sings of colibaccillosis was established in control group and infected mice was died. Conclusion. Overuse antibiotics developed serious new types of multi drug resistance in human medicine and therefore has limited their use in farm animals. The study indicates the use of Colicin and biotherapy instead of antibiotic is more safe and efficient for control of E. coliK99 infection. Immunized mice by Colicin solution protected E. coli K99 colonization and reduce fecal shedding. Investigation in livestock for applying Colicin in farm animal is recommended.

  11. Cost-effective expression and purification of antimicrobial and host defense peptides in Escherichia coli

    DEFF Research Database (Denmark)

    Bommarius, B.; Jenssen, Håvard; Elliott, M.

    2010-01-01

    Cationic antimicrobial host defense peptides (HDPs) combat infection by directly killing a wide variety of microbes, and/or modulating host immunity. HDPs have great therapeutic potential against antibioticresistant bacteria, viruses and even parasites, but there are substantial roadblocks......, we describe (i) a method, using fusions to SUMO, for producing high yields of intact recombinant HDPs in bacteria without significant toxicity and (ii) a simplified 2-step purification method appropriate for industrial use. We have used this method to produce seven HDPs to date (IDR1, MX226, LL37......, CRAMP, HHC-10, E5 and E6). Using this technology, pilot-scale fermentation (10 L) was performed to produce large quantities of biologically active cationic peptides. Together, these data indicate that this new method represents a cost-effective means to enable commercial enterprises to produce HDPs...

  12. Modeling the effect of Rose Bengal on growth and decay patterns of Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus

    Science.gov (United States)

    Al-Akhras, M.-Ali H.; Shorman, Mohammad Al; Masadeh, Majed M.; Aljarrah, Khaled; Ababneh, Zaid

    2018-02-01

    Most infections caused by (Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus) are hospital and community acquired infections in patients. Bacterial growths incorporated with photosensitizing material (Rose Bengal) with and without light were investigated. The results demonstrated that the viable counts are increasing in absence of light (in dark) for all samples incorporated with Rose Bengal. Variation in growth phases were noticed as expected, but there is no significant change in decay phases. Convenient and adequate mathematical modeling is in very good agreement with the experimental results and showed to be a very good approach of characterization the growth behaviors of the bacteria. Bandwidths are independent of bacteria group (gram-positive or gram-negative) but it seems totally dependent on the oxygen requirements; an anaerobic bacterium takes broader bandwidths than aerobic bacteria. This concludes that the growth and lethal rates of anaerobic are much greater than aerobic.

  13. Effects of divalent cations, EDTA and chitosan on the uptake and photoinactivation of Escherichia coli mediated by cationic and anionic porphyrins.

    Science.gov (United States)

    Gsponer, Natalia S; Spesia, Mariana B; Durantini, Edgardo N

    2015-03-01

    The effect of divalent cations, EDTA and chitosan (CS) on the uptake and photoinactivation of Escherichia coli produced by 5,10,15,20-tetrakis(4-N,N,N-trimethylammoniumphenyl)porphyrin (TMAP(4+)), 5,10-di(4-methylphenyl)-15,20-di(4-N,N,N-trimethylammoniumphenyl)porphyrin (MPAP(2+)) and 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS(4-)) were examined under different conditions. These porphyrins were rapidly bound to E. coli cells (TMAP(4+), MPAP(2+) and TPPS(4-), respectively. The addition of Ca(2+) or Mg(2+) to the cultures enhanced the uptake of MPAP(2+) and TPPS(4-) by cells. In contrast, the amount of TMAP(4+) bound to cells was decreased. The presence of EDTA produced an increase in the uptake of porphyrins by cells, while CS mainly enhanced the amount of TPPS(4-) bound to E. coli. The photoinactivation of E. coli cells mediated by TMAP(4+) was highly effective even at low concentration (1μM) and short irradiation period (5min). However, a reduction in the phototoxicity was found for TMAP(4+) in presence of Ca(2+) and Mg(2+). In contrast, the phototoxic activity mediated by MPAP(2+) and TPPS(4-) was increased. Addition of EDTA did not show effect on the photoinactivation induced by cationic porphyrins, while a small enhance was found for TPPS(4-). Moreover, inactivation of E. coli cells was achieved in the presence CS. This cationic polymer was antimicrobial by itself in the dark. Using a slightly toxic CS concentration, the phototoxic activity induced by TMAP(4+) was diminished. This effect was mainly observed at lower concentration of TMAP(4+) (0.5-1μM). In contrast, an increase in E. coli photoinactivation was obtained for MPAP(2+) and TPPS(4-) in presence of CS. Thus, this natural polymeric destabilizer agent mainly benefited the photoinactivation mediated by TPPS(4-). Copyright © 2014 Elsevier B.V. All rights reserved.

  14. The effect of sorbic acid and esters of p-hydroxybenzoic acid on the protonmotive force in Escherichia coli membrane vesicles.

    Science.gov (United States)

    Eklund, T

    1985-01-01

    The effect of three food preservatives, sorbic acid and methyl and butyl esters of p-hydroxybenzoic acid, on the protonmotive force in Escherichia coli membrane vesicles was investigated. Radioactive chemical probes were used to determine the two components of the protonmotive force: delta pH (pH difference) and delta psi (membrane potential). Both types of compound selectively eliminated delta pH across the membrane, while leaving delta psi much less disturbed indicating that transport inhibition by neutralization of the protonmotive force cannot be the only mechanism of action for the food preservatives tested.

  15. Effect of Salvia chorassanica Root Aqueous, Ethanolic and Hydro Alcoholic Extracts on Staphylococcus aureus, Enterococcus faecalis, Salmonella typhimurium and Escherichia coli

    Directory of Open Access Journals (Sweden)

    Azam Mehraban

    2016-11-01

    Full Text Available Background Nowadays, through the previous researches, it has become clear that Salvia has important health benefits. Salvia chorassanica is one of the valuable native Iranian species which only grows in Khorasan province, Iran. Objectives The aim of this study is to evaluate the antimicrobial effect of Salvia chorassanica root aqueous, ethanolic and hydro alcoholic extracts on Staphylococcus aureus, Enterococcus faecalis, Salmonella typhimurium and Escherichia coli. Methods In this experimental study, maceration method was used to prepare extracts. Study setup was conducted in March 2014.The duration of study setup took for two months. The micro dilution method by ELISA was used to determine the minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC of aqueous, ethanolic and hydro alcoholic extracts of root of Salvia chorassanica against Staphylococcus aureus, Enterococcus faecalis, Salmonella typhimurium and Escherichia coli. The antibacterial effect also was evaluated using agar diffusion method. The inhibition zones of growth against the extracts were measured in comparison to standards antibiotics. Chloramphenicol as positive control on Enterococcus faecalis, Tetracycline on Staphylococcus aureus, Gentamicin on Escherichia coli and Neomycin on Salmonella typhimurium. The data were analyzed using one way analysis of variance (ANOVA with SPSS version 16. Results The highest inhibition zone in diffusion method was related to ethanolic extract of Salvia chorassanica root against Gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis. The calculated MIC in aqueous and ethanolic extracts of root for Staphylococcus aureus was 240 and 120 mg/mL, for Enterococcus faecalis was 120 and 60 mg/mL respectively, and for Escherichia coli and Salmonella typhimurium was equal to 240 mg/mL. The amount in hydro alcoholic extracts for Gram-positive bacteria was 60 mg/mL and for Gram-negative bacteria was 120 mg/mL. The

  16. Distribution of Diverse Escherichia coli between Cattle and Pasture

    OpenAIRE

    NandaKafle, Gitanjali; Seale, Tarren; Flint, Toby; Nepal, Madhav; Venter, Stephanus N.; Brözel, Volker S.

    2017-01-01

    Escherichia coli is widely considered to not survive for extended periods outside the intestines of warm-blooded animals; however, recent studies demonstrated that E. coli strains maintain populations in soil and water without any known fecal contamination. The objective of this study was to investigate whether the niche partitioning of E. coli occurs between cattle and their pasture. We attempted to clarify whether E. coli from bovine feces differs phenotypically and genotypically from isola...

  17. Effects of Cinnamon extract on biochemical enzymes, TNF-α and NF-κB gene expression levels in liver of broiler chickens inoculated with Escherichia coli

    Directory of Open Access Journals (Sweden)

    Seyed Mahmoud Tabatabaei

    2015-09-01

    Full Text Available Abstract: Infection with Escherichia coli (E. coli is a common disease in poultry industry. The use of antibiotics to treat diseases is facing serious criticism and concerns. The medicinal plants may be effective alternatives because of their multiplex activities. The aim of this study was to investigate the effects of cinnamon extract on the levels of liver enzymes, tumor necrosis factor-alpha (TNF-α and nuclear factor-kappa B (NF-κB gene expressions in liver of broiler chickens infected with E. coli. Ninety Ross-308 broilers were divided into healthy or E. coli-infected groups, receiving normal or cinnamon extract (in concentrations of 100 or 200mg/kg of food supplemented diets. E. coli suspension (108cfu was injected subcutaneously after 12 days cinnamon administration. Seventy-two hours after E. coli injection, the blood samples were taken for biochemical analysis of liver enzymes in serum (spectrophotometrically, and liver tissue samples were obtained for detection of gene expression of inflammatory markers TNF-α and NF-κB, using real-time PCR. Infection with E. coli significantly increased the levels of TNF-α and NF-κB gene expressions as well as some liver enzymes including creatine-kinase (CK, lactate-dehydrogenase (LDH, alanine-transferase (ALT and aspartate-transferase (AST as compared with control group (P<0.05. Pre-administration of cinnamon extract in broilers diet (in both concentrations significantly reduced the tissue levels of TNF-α and NF-κB gene expressions and enzymes CK and ALT in serum of broiler chickens inoculated with E. coli in comparison with E. coli group (P<0.05 and P<0.01. The levels of LDH and AST were significantly decreased only by 200mg/kg cinnamon extract in infected broilers. The level of alkaline-phosphatase (ALP was not affected in any groups. Pre-administration of cinnamon extract in diets of broiler chickens inoculated with E. coli could significantly reduce the gene expression levels of pro

  18. Genetic Transfer of Salmonella typhimurium and Escherichia coli Lipopolysaccharide Antigens to Escherichia coli K-12

    Science.gov (United States)

    Jones, Randall T.; Koeltzow, Donald E.; Stocker, B. A. D.

    1972-01-01

    Escherichia coli K-12 ϰ971 was crossed with a smooth Salmonella typhimurium donor, HfrK6, which transfers early the ilv-linked rfa region determining lipopolysaccharide (LPS) core structure. Two ilv+ hybrids differing in their response to the LPS-specific phages FO and C21 were then crossed with S. typhimurium HfrK9, which transfers early the rfb gene cluster determining O repeat unit structure. Most recombinants selected for his+ (near rfb) were agglutinated by Salmonella factor 4 antiserum. Transfer of an F′ factor (FS400) carrying the rfb–his region of S. typhimurium to the same two ilv+ hybrids gave similar results. LPS extracted from two ilv+,his+, factor 4-positive hybrids contained abequose, the immunodominant sugar for factor 4 specificity. By contrast, his+ hybrids obtained from ϰ971 itself by similar HfrK9 and F′FS400 crosses were not agglutinated by factor 4 antiserum, indicating that the parental E. coli ϰ971 does not have the capacity to attach Salmonella O repeat units to its LPS core. It is concluded that the Salmonella rfb genes are expressed only in E. coli ϰ971 hybrids which have also acquired ilv-linked genes (presumably rfa genes affecting core structure or O-translocase ability, or both) from a S. typhimurium donor. When E. coli ϰ971 was crossed with a smooth E. coli donor, Hfr59, of serotype O8, which transfers his early, most his+ recombinants were agglutinated by E. coli O8 antiserum and lysed by the O8-specific phage, Ω8. This suggests that, although the parental E. coli K-12 strain ϰ971 cannot attach Salmonella-specific repeat units to its LPS core, it does have the capacity to attach E. coli O8-specific repeat units. PMID:4559827

  19. A metabolomics-based method for studying the effect of yfcC gene in Escherichia coli on metabolism.

    Science.gov (United States)

    Wang, Xiyue; Xie, Yuping; Gao, Peng; Zhang, Sufang; Tan, Haidong; Yang, Fengxu; Lian, Rongwei; Tian, Jing; Xu, Guowang

    2014-04-15

    Metabolomics is a potent tool to assist in identifying the function of unknown genes through analysis of metabolite changes in the context of varied genetic backgrounds. However, the availability of a universal unbiased profiling analysis is still a big challenge. In this study, we report an optimized metabolic profiling method based on gas chromatography-mass spectrometry for Escherichia coli. It was found that physiological saline at -80°C could ensure satisfied metabolic quenching with less metabolite leakage. A solution of methanol/water (21:79, v/v) was proved to be efficient for intracellular metabolite extraction. This method was applied to investigate the metabolome difference among wild-type E. coli, its yfcC deletion, and overexpression mutants. Statistical and bioinformatic analysis of the metabolic profiling data indicated that the expression of yfcC potentially affected the metabolism of glyoxylate shunt. This finding was further validated by real-time quantitative polymerase chain reactions showing that expression of aceA and aceB, the key genes in glyoxylate shunt, was upregulated by yfcC. This study exemplifies the robustness of the proposed metabolic profiling analysis strategy and its potential roles in investigating unknown gene functions in view of metabolome difference. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Effect of mutagens, chemotherapeutic agents and defects in DNA repair genes on recombination in F' partial diploid Escherichia coli

    International Nuclear Information System (INIS)

    Norin, A.J.; Goldschmidt, E.P.

    1979-01-01

    The ability of mutagenic agents, nonmutagenic substances and defects in DNA repair to alter the genotype of F' partial diploid (F30) Escherichia coli was determined. The frequency of auxotrophic mutants and histidine requiring (His - ) haploid colonies was increased by mutagen treatment but Hfr colonies were not detected in F30 E. coli even with specific selection techniques. Genotype changes due to nonreciprocal recombination were determined by measuring the frequency of His - homogenotes, eg. F' hisC780, hisI + /hisC780, hisI + , arising from a His + heterogenote, F' hisC780 hisI + /hisC + , his1903. At least 75% of the recombinants were homozygous for histidine alleles which were present on the F' plasmid (exogenote) of the parental hetergenote rather than for histidine alleles on the chromosome. Mutagens, chemotherapeutic agents which block DNA synthesis and a defective DNA polymerase I gene, polA1, were found to increase the frequency of nonreciprocal recombination. A defect in the ability to excise thymine dimers, uvrC34, did not increase spontaneous nonreciprocal recombination. However, UV irradiation but not methyl methanesulfonate (MMS) induced greater recombination in this excision-repair defective mutant than in DNA-repair-proficient strains. (Auth.)

  1. Effect of bacterial components of mixed culture supernatants of planktonic and biofilm Pseudomonas aeruginosa with commensal Escherichia coli on the neutrophil response in vitro.

    Science.gov (United States)

    Maslennikova, Irina L; Kuznetsova, Marina V; Nekrasova, Irina V; Shirshev, Sergei V

    2017-11-30

    Pseudomonas aeruginosa (PA) responsible for acute and chronic infections often forms a well-organized bacterial population with different microbial species including commensal strains of Escherichia coli. Bacterial extracellular components of mixed culture can modulate the influence of bacteria on the neutrophil functions. The objective of this study was to compare the effect of pyocyanin, pyoverdine, LPS, exopolysaccharide of single species and mixed culture supernatants of PA strains and E. coli K12 on microbicidal, secretory activity of human neutrophils in vitro. Bacterial components of E. coli K12 in mixed supernatants with 'biofilm' PA strains (PA ATCC, PA BALG) enhanced short-term microbicidal mechanisms and inhibited neutrophil secretion delayed in time. The influence of 'planktonic' PA (PA 9-3) exometabolites in mixed culture is almost mimicked by E. coli K12 effect on functional neutrophil changes. This investigation may help to understand some of the mechanisms of neutrophil response to mixed infections of different PA with other bacteria species. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Effects of selection pressure and genetic association on the relationship between antibiotic resistance and virulence in Escherichia coli.

    Science.gov (United States)

    Zhang, Lixin; Levy, Karen; Trueba, Gabriel; Cevallos, William; Trostle, James; Foxman, Betsy; Marrs, Carl F; Eisenberg, Joseph N S

    2015-11-01

    Antibiotic selection pressure and genetic associations may lead to the cooccurrence of resistance and virulence in individual pathogens. However, there is a lack of rigorous epidemiological evidence that demonstrates the cooccurrence of resistance and virulence at the population level. Using samples from a population-based case-control study in 25 villages in rural Ecuador, we characterized resistance to 12 antibiotics among pathogenic (n = 86) and commensal (n = 761) Escherichia coli isolates, classified by the presence or absence of known diarrheagenic virulence factor genes. The prevalences of resistance to single and multiple antibiotics were significantly higher for pathogenic isolates than for commensal isolates. Using a generalized estimating equation, antibiotic resistance was independently associated with virulence factor carriage, case status, and antibiotic use (for these respective factors: odds ratio [OR] = 3.0, with a 95% confidence interval [CI] of 1.7 to 5.1; OR = 2.0, with a 95% CI of 1.3 to 3.0; and OR = 1.5, with a 95% CI of 0.9 to 2.5). Virulence factor carriage was more strongly related to antibiotic resistance than antibiotic use for all antibiotics examined, with the exception of fluoroquinolones, gentamicin, and cefotaxime. This study provides epidemiological evidence that antibiotic resistance and virulence factor carriage are linked in E. coli populations in a community setting. Further, these data suggest that while the cooccurrence of resistance and virulence in E. coli is partially due to antibiotic selection pressure, it is also genetically determined. These findings should be considered in developing strategies for treating infections and controlling for antibiotic resistance. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  3. Complete Genome Sequence of Escherichia coli Strain WG5

    DEFF Research Database (Denmark)

    Imamovic, Lejla; Misiakou, Maria-Anna; van der Helm, Eric

    2018-01-01

    Escherichia coli strain WG5 is a widely used host for phage detection, including somatic coliphages employed as standard ISO method 10705-1 (2000). Here, we present the complete genome sequence of a commercial E. coli WG5 strain.......Escherichia coli strain WG5 is a widely used host for phage detection, including somatic coliphages employed as standard ISO method 10705-1 (2000). Here, we present the complete genome sequence of a commercial E. coli WG5 strain....

  4. Effects of sugarcane juice addition on the population dynamics of Escherichia coli and the presence of Shiga-toxigenic E. coli during the anaerobic codigestion of dairy cattle manure

    Directory of Open Access Journals (Sweden)

    Paula Maria Pilotto Branco

    2018-03-01

    Full Text Available ABSTRACT: The objective of this study was to evaluate the effects of the addition of sugarcane juice on the population dynamics of Escherichia coli and the presence of Shiga-toxigenic E. coli (STEC during the anaerobic codigestion of dairy cattle manure. For the overall analyses at the end of a hydraulic retention time of 90 days, ten two-liter batch-type biodigesters were divided into two treatment groups: biodigester containing manure and water (MW and the biodigester containing manure, water and sugarcane juice (MSC. For monitoring the population dynamics and presence of microorganisms, pH, and volatile acidity, tests were carried out every ten days, on 36 smaller-scale batch biodigesters made of one-liter plastic bottles (18 for each treatment. The reductions in E. coli population over time were significant in the MW (60 days and MSC (20 days biodigesters. Inactivation of STEC occurred in a shorter period (40 days in MW and <10 days in MSC. Significant differences were obtained between the two treatments, with the pH values being lower, the concentrations of volatile acids (VA being higher, and the inactivation of E. coli and STEC being faster in the biodigester with sugarcane juice added. The amount of sugarcane juice applied (7% suggests its suitability for the sanitization of dairy cattle manure for use as a biofertilizer, given the high reduction in the E. coli population and inactivation of STEC.

  5. PENGARUH PERASAN DAUN BELIMBING WULUH (Averrhoa bilimbi TERHADAP PERTUMBUHAN BAKTERI Escherichia coli PATOGEN

    Directory of Open Access Journals (Sweden)

    Fitrotin Azizah

    2017-12-01

    abstract  (Averrhoa bilimbi is one of the plants that can be used as an antibacterial, good flowers, stems, leaves and stems have benefits and efficacy. Chemical constituents of the leaves starfruit are tannins, flavonoids, saponins. The active ingredient in the leaves starfruit is tannin. Escherichia coli is a bacterium that causes diarrhea. From the above discussion, the authors raised the theme of Influence starfruit juice of the leaves on the growth of pathogenic E. coli bacteria. Formulation of the problem researchers is whether there is influence starfruit juice of the leaves on the growth of Escherichia coli pathogens. This study aims to determine the concentration that could inhibit and kill Esherichia coli Escherichia coli. This research is experimental. The sample used is leaf green starfruit not so young in a fresh state taken in the area around the boarding author Sutorejo 11B stay. In this study, the sample size for each treatment as much as 3 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10% and C (control. Independent variables are starfruit juice of the leaves, while the dependent variable growth of Escherichia coli. When the study carried out in January and July 2012. Data on the effect of starfruit juice of the leaves on the growth of Escherichia coli tested by laboratory examination and data collection techniques using Chi-Square 0:05. Based on the results it appears that at a concentration of 100% and 90% were able to kill the bacteria Escherichia coli, whereas the inhibitory power ranging from a concentration of 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%. From Chi-Square test was obtained λ2 count effect on the growth of Escherichia coli pathogenic bacteria. Keyword : Leaves starfruit, E. Coli

  6. Multifactorial effects of ambient temperature, precipitation, farm management, and environmental factors determine the level of generic Escherichia coli contamination on preharvested spinach.

    Science.gov (United States)

    Park, Sangshin; Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Jun, Mikyoung; Han, Daikwon; Lawhon, Sara; Ivanek, Renata

    2015-04-01

    A repeated cross-sectional study was conducted to identify farm management, environment, weather, and landscape factors that predict the count of generic Escherichia coli on spinach at the preharvest level. E. coli was enumerated for 955 spinach samples collected on 12 farms in Texas and Colorado between 2010 and 2012. Farm management and environmental characteristics were surveyed using a questionnaire. Weather and landscape data were obtained from National Resources Information databases. A two-part mixed-effect negative binomial hurdle model, consisting of a logistic and zero-truncated negative binomial part with farm and date as random effects, was used to identify factors affecting E. coli counts on spinach. Results indicated that the odds of a contamination event (non-zero versus zero counts) vary by state (odds ratio [OR] = 108.1). Odds of contamination decreased with implementation of hygiene practices (OR = 0.06) and increased with an increasing average precipitation amount (mm) in the past 29 days (OR = 3.5) and the application of manure (OR = 52.2). On contaminated spinach, E. coli counts increased with the average precipitation amount over the past 29 days. The relationship between E. coli count and the average maximum daily temperature over the 9 days prior to sampling followed a quadratic function with the highest bacterial count at around 24°C. These findings indicate that the odds of a contamination event in spinach are determined by farm management, environment, and weather factors. However, once the contamination event has occurred, the count of E. coli on spinach is determined by weather only. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  7. Antibacterial effect evaluation of moxalactam against extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae with in vitro pharmacokinetics/pharmacodynamics simulation

    Directory of Open Access Journals (Sweden)

    Huang C

    2018-01-01

    Full Text Available Chen Huang,1,* Beiwen Zheng,1,* Wei Yu,2 Tianshui Niu,1 Tingting Xiao,1 Jing Zhang,1 Yonghong Xiao1 1State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; 2Department of Infectious Diseases, Zhejiang Provincial People’s Hospital, Hangzhou, China *These authors contributed equally to this work Objectives: The aim of this study was to evaluate the bactericidal effects of moxalactam (MOX, cefotaxime (CTX, and cefoperazone/sulbactam (CFZ/SBT against extended-spectrum β-lactamase (ESBL producing Escherichia coli and Klebsiella pneumoniae, using an in vitro pharmacokinetics (PK/pharmacodynamics model.Methods: Two clinical ESBL-producing strains (blaCTX-M-15 positive E. coli 3376 and blaCTX-M-14 positive K. pneumoniae 2689 and E. coli American Type Culture Collection (ATCC25922 were used in the study. The PK Auto Simulation System 400 was used to simulate the human PK procedures after intravenous administration of different doses of MOX, CTX, and CFZ/SBT. Bacterial growth recovery time (RT and the area between the control growth curve and bactericidal curves (IE were employed to assess the antibacterial efficacies of all the agents.Results: The minimum inhibitory concentrations of MOX, CTX, and CFZ/SBT against E. coli ATCC25922, 3376, and 2689 strains were 0.5, 0.5, 0.25; 0.06, >256, 256; and 0.5/0.5, 16/16, 32/32 mg/L. All the agents demonstrated outstanding bactericidal effects against E. coli ATCC25922 (RT >24 h and IE >120 log10 CFU/mL·h−1 with simulating PK procedures, especially in the multiple dose administration models. Against ESBL producers, CTX and CFZ/SBT displayed only weak bactericidal effects, and subsequent regrowth was evident. MOX exhibited potent antibacterial activity against all the strains tested. The values of effective parameters of

  8. The effect of an extract from Ganoderma lucidum (reishi on the labeling of blood constituents with technetium-99m and on the survival of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Raquel Terra Agostinho

    2008-12-01

    Full Text Available This study evaluated effects of an aqueous extract of Ganoderma lucidum (reishi on the labeling of blood constituents with technetium-99m (99mTc and on the survival of cultures of Escherichia coli treated with stannous chloride. Blood samples from Wistar rats were treated with reishi extract, radiolabeling procedure was performed, plasma (P, blood cells (BC and insoluble (IF and soluble (SF fractions of P and BC were separated. The radioactivity was counted for the determination of the percentages of radioactivity (%ATI. Cultures of Escherichia coli AB1157 were treated with stannous chloride in the presence and absence of reishi extract. Blood samples and bacterial cultures treated with NaCl 0.9% were used as controls. Data indicated that reishi extract altered significantly (pEste estudo avaliou efeitos de um extrato de Ganoderma lucidum (reishi na marcação de constituintes sangüíneos com tecnécio-99m (99mTc e na sobrevivência de culturas de Escherichia coli tratadas com cloreto estanoso. Amostras de sangue de ratos Wistar foram tratadas com extrato de reishi, o procedimento de radiomarcação foi realizado, plasma (P, células sangüíneas (CS e frações insolúvel (FI e solúvel (FS de P e CS foram separadas e a radioatividade foi contada para determinação das porcentagens de radioatividade (%ATI. Culturas de Escherichia coli AB1157 foram tratadas com cloreto estanoso na presença e ausência do extrato de reishi. Amostras de sangue e culturas bacterianas tratadas com NaCl 0.9% foram usadas como controles. Dados indicaram que o extrato de reishi alterou significativamente (p<0,05 a %ATI de P, CS, FI-P, FS-P, FI-CS e FS-CS, bem como, aumentou a sobrevivência de culturas bacterianas tratadas com cloreto estanoso. Nossos resultados sugerem que o extrato de reishi poderia apresentar ação redox/quelante alterando a marcação de constituintes sangüíneos com 99mTc e protegendo culturas bacterianas contra lesões oxidativas induzidas

  9. Effects of casein glycomacropeptide supplementation on growth performance, intestinal morphology, intestinal barrier permeability and inflammatory responses in Escherichia coli K88 challenged piglets

    Directory of Open Access Journals (Sweden)

    Yili Rong

    2015-06-01

    Full Text Available Casein glycomacropeptide (CGMP is a bioactive peptide derived from milk with multiple functions. This study was aimed at evaluating the effects of CGMP as a potential feed additive on growth performance, intestinal morphology, intestinal barrier permeability and inflammatory responses of Escherichia coli K88 (E. coli K88 challenged piglets. Eighteen weaning piglets were randomly assigned to three groups. Control group and K88 challenged group received a basal diet, and CGMP treated group received the basal diet supplemented with 1% of CGMP powder. The trail lasted for 12 days, K88 was orally administered to the piglets of K88 challenged group and CGMP treated group on days 8–10. The results showed that the diet containing 1% CGMP significantly alleviated the decrease in average daily gain (P  0.05 and barrier permeability damage (P < 0.05, and acute inflammatory response (P < 0.05 induced by E. coli K88 infection. In conclusion, CGMP supplementation in the diet protected the weaning piglets against E. coli K88 infection.

  10. TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI

    Science.gov (United States)

    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...

  11. The Prevalence of Enterhaemorrhagic Escherichia Coli in children ...

    African Journals Online (AJOL)

    EHEC), the pathogenicity of other strains of Escherichia coli and other organisms in children presenting with and without diarrhoea in the hospital. Subjects and Methods: A total of 247 stool samples collected from children aged 1 month to 7 ...

  12. GLYCOSYLATED YGHJ POLYPEPTIDES FROM ENTEROTOXIGENIC ESCHERICHIA COLI (ETEC)

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates to glycosylated YghJ polypeptides from or derived from enterotoxigenic Escherichia coli (ETEC) that are immunogenic. In particular, the present invention relates to compositions or vaccines comprising the polypeptides and their application in immunization, vaccination...

  13. Toxicity mechanism of carbon nanotubes on Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Young, Yu-Fu [Department of Materials Science and Engineering, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Lee, Hui-Ju [Department of Life Science, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Shen, Yi-Shan; Tseng, Shih-Hao; Lee, Chi-Young [Department of Materials Science and Engineering, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Tai, Nyan-Hwa, E-mail: nhtai@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Chang, Hwan-You, E-mail: hychang@mx.nthu.edu.tw [Department of Life Science, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer F-MWCNTs possess higher antibiotic performance than that of the F-SWCNTs. Black-Right-Pointing-Pointer E. coli cells were pierced when incubated with F-MWCNTs and trapped when incubated with F-SWCNTs. Black-Right-Pointing-Pointer The rigidity and moment of CNTs play important role on the antibiotic effect. - Abstract: The influences of carbon nanomaterials on bacteria were investigated using three types of dispersed and functionalized carbon nanomaterials (F-CNMs), viz. functionalized carbon nanopowder (F-CNP), functionalized single-walled carbon nanotubes (F-SWCNTs), and functionalized multi-walled carbon nanotubes (F-MWCNTs). F-CNMs with different aspect ratios were used to study the influence of material configuration on the viability of Escherichia coli (E. coli). Although these materials were functionalized to improve their dispersibility, the original morphologies and chemical properties of the materials were maintained. Traditional bacteria quantitative plating analysis was conducted, and the results of which revealed that the F-CNP and the F-SWCNTs showed a less significant effect on the viability of E. coli, while the F-MWCNTs obviously inhibited cell viability. A Fourier transform infrared spectroscopy and a scanning electron microscopy were used to verify the functionalization of the F-CNMs and to examine the interaction of F-CNMs with E. coli, respectively; in addition, we adopted chemiluminescence assays to measure the concentration of adenosine triphosphate (ATP) released from the damaged cells. The results showed that the ATP of the F-MWCNTs sample is two-fold higher than that of the control, indicating direct piercing of E. coli by F-MWCNTs leads to bacteria death. Furthermore, F-SWCNTs were concluded to have less influence on the viability of E. coli because ultra-long F-SWCNTs used in this study performed less rigidity to pierce the cells.

  14. Toxicity mechanism of carbon nanotubes on Escherichia coli

    International Nuclear Information System (INIS)

    Young, Yu-Fu; Lee, Hui-Ju; Shen, Yi-Shan; Tseng, Shih-Hao; Lee, Chi-Young; Tai, Nyan-Hwa; Chang, Hwan-You

    2012-01-01

    Highlights: ► F-MWCNTs possess higher antibiotic performance than that of the F-SWCNTs. ► E. coli cells were pierced when incubated with F-MWCNTs and trapped when incubated with F-SWCNTs. ► The rigidity and moment of CNTs play important role on the antibiotic effect. - Abstract: The influences of carbon nanomaterials on bacteria were investigated using three types of dispersed and functionalized carbon nanomaterials (F-CNMs), viz. functionalized carbon nanopowder (F-CNP), functionalized single-walled carbon nanotubes (F-SWCNTs), and functionalized multi-walled carbon nanotubes (F-MWCNTs). F-CNMs with different aspect ratios were used to study the influence of material configuration on the viability of Escherichia coli (E. coli). Although these materials were functionalized to improve their dispersibility, the original morphologies and chemical properties of the materials were maintained. Traditional bacteria quantitative plating analysis was conducted, and the results of which revealed that the F-CNP and the F-SWCNTs showed a less significant effect on the viability of E. coli, while the F-MWCNTs obviously inhibited cell viability. A Fourier transform infrared spectroscopy and a scanning electron microscopy were used to verify the functionalization of the F-CNMs and to examine the interaction of F-CNMs with E. coli, respectively; in addition, we adopted chemiluminescence assays to measure the concentration of adenosine triphosphate (ATP) released from the damaged cells. The results showed that the ATP of the F-MWCNTs sample is two-fold higher than that of the control, indicating direct piercing of E. coli by F-MWCNTs leads to bacteria death. Furthermore, F-SWCNTs were concluded to have less influence on the viability of E. coli because ultra-long F-SWCNTs used in this study performed less rigidity to pierce the cells.

  15. Lon gene and photoprotection in Escherichia coli K-12

    Energy Technology Data Exchange (ETDEWEB)

    Waksman, G.; Thomas, G.; Favre, A. (Institut de Recherche en Biologie Moleculaire, Group de Photobiologie Moleculaire, Paris (France))

    1984-03-01

    Photoprotection, i.e. the increased resistance of the cells preilluminated with near ultraviolet light (300-380 nm) to the lethal action of 254nm radiations requires either an integrated prophage or a recA mutation in Escherichia coli K12 strains. Significant photoprotection occurs in an Escherichia coli K12 recA/sup +/ cell containing the lon allele responsible for filamentous growth after 254nm irradiation. The Fil phenotype can be suppressed by the sfiA or sfiB suppressor genes. Since the E. coli K12 recA/sup +/ lon sfiB strain exhibits no more photoprotection, it is concluded that in lon strains photoprotection is due to the abolition of the 254nm induced filamentation by the near ultraviolet treatment. In addition, near ultraviolet illumination of the cells leads to a severe restriction of the bulk protein synthesis. This effect is observed only in nuv/sup +/ cells that contain 4-thiouridine the chromophore responsible for photoprotection. It is proposed that in lon (lysogenic strains) photoprotection is due to prevention of the SOS response. During the growth lag, the low residual level of protein synthesis does not allow the induction of the SOS response and accordingly prevents filamentation (the lytic cycle).

  16. The lon gene and photoprotection in Escherichia coli K-12

    International Nuclear Information System (INIS)

    Waksman, G.; Thomas, G.; Favre, A.

    1984-01-01

    Photoprotection, i.e. the increased resistance of the cells preilluminated with near ultraviolet light (300-380 nm) to the lethal action of 254nm radiations requires either an integrated prophage or a recA mutation in Escherichia coli K12 strains. Significant photoprotection occurs in an Escherichia coli K12 recA + cell containing the lon allele responsible for filamentous growth after 254nm irradiation. The Fil phenotype can be suppressed by the sfiA or sfiB suppressor genes. Since the E. coli K12 recA + lon sfiB strain exhibits no more photoprotection, it is concluded that in lon strains photoprotection is due to the abolition of the 254nm induced filamentation by the near ultraviolet treatment. In addition, near ultraviolet illumination of the cells leads to a severe restriction of the bulk protein synthesis. This effect is observed only in nuv + cells that contain 4-thiouridine the chromophore responsible for photoprotection. It is proposed that in lon (lysogenic strains) photoprotection is due to prevention of the SOS response. During the growth lag, the low residual level of protein synthesis does not allow the induction of the SOS response and accordingly prevents filamentation (the lytic cycle). (author)

  17. Effect of rifampicin and gentamicin on Shiga toxin 2 expression level and the SOS response in Escherichia coli O104:H4.

    Science.gov (United States)

    Fadlallah, Sukayna M; Rahal, Elias A; Sabra, Ahmad; Kissoyan, Kohar A B; Matar, Ghassan M

    2015-01-01

    A novel pathotype, Shiga toxin-producing Escherichia coli O104:H4, was the cause of a severe outbreak that affected European countries, mainly Germany, in 2011. The effect of different regimens of rifampicin and gentamicin were evaluated to determine possible treatment modes for the novel strain, and to evaluate the SOS response and its effect on toxin release. Pulsed-field gel electrophoresis (PFGE) was performed on the novel E. coli O104:H4 pathotype and two pre-outbreak E. coli O104:H4 CDC strains. Transcript levels of the stx2 and recA gene (SOS response inducer) were evaluated using quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) in the novel E. coli O104:H4 samples subjected to different regimens of rifampicin and gentamicin. Consequently, reverse passive latex agglutination (RPLA) was used to determine the Stx2 titers in these samples. Western blot was performed to determine the LexA levels (SOS response repressor) in E. coli O104:H4. The efficacy of treatment with antimicrobial agents was assessed in BALB/c mice. The outbreak and pre-outbreak strains are closely related as shown by PFGE, which demonstrated slight genomic differences between the three strains. The transcription level of the stx2 gene in the new pathotype was 1.41- and 1.75-fold that of the 2009 EL-2050 and 2009 EL-2071 pre-outbreak strains, respectively. Moreover, the transcription level of the stx2 gene in the new pathotype was substantially decreased as a result of treatment with the different concentrations of the antimicrobial agents, but was enhanced when the antibiotics were administered at two subinhibitory levels. RPLA data were in accordance with the qRT-PCR results. E. coli O104:H4 exposed to gentamicin at both sub-minimum inhibitory concentration (MIC) levels led to high transcription levels of the recA gene and lack of expression of the LexA protein, implying that the SOS response was activated. Rifampicin at both sub-MIC levels resulted in low

  18. Hemolytic porcine intestinal Escherichia coli without virulence-associated genes typical of intestinal pathogenic E. coli.

    Science.gov (United States)

    Schierack, Peter; Weinreich, Joerg; Ewers, Christa; Tachu, Babila; Nicholson, Bryon; Barth, Stefanie

    2011-12-01

    Testing 1,666 fecal or intestinal samples from healthy and diarrheic pigs, we obtained hemolytic Escherichia coli isolates from 593 samples. Focusing on hemolytic E. coli isolates without virulence-associated genes (VAGs) typical for enteropathogens, we found that such isolates carried a broad variety of VAGs typical for extraintestinal pathogenic E. coli.

  19. A novel model to study neonatal Escherichia coli sepsis and the effect of treatment on the human immune system using humanized mice.

    Science.gov (United States)

    Schlieckau, Florian; Schulz, Daniela; Fill Malfertheiner, Sara; Entleutner, Kathrin; Seelbach-Goebel, Birgit; Ernst, Wolfgang

    2018-04-19

    Neonatal sepsis is a serious threat especially for preterm infants. As existing in vitro and in vivo models have limitations, we generated a novel neonatal sepsis model using humanized mice and tested the effect of Betamethasone and Indomethacin which are used in the clinic in case of premature birth. Humanized mice were infected with Escherichia coli (E. coli). Subsequently, the effect of the infection itself, and treatment with Betamethasone and Indomethacin on survival, recovery, bacterial burden, leukocyte populations, and cytokine production, was analyzed. The human immune system in the animals responded with leukocyte trafficking to the site of infection and granulopoiesis in the bone marrow. Treatment with Indomethacin had no pronounced effect on the immune system or bacterial burden. Betamethasone induced a decline of splenocytes. The human immune system in humanized mice responds to the infection, making them a suitable model to study neonatal E. coli sepsis and the immune response of the neonatal immune system. Treatment with Betamethasone could have potential negative long-term effects for the immune system of the child. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. TiO2 Photocatalysis Damages Lipids and Proteins in Escherichia coli

    NARCIS (Netherlands)

    Carre, Gaelle; Hamon, Erwann; Ennahar, Said; Estner, Maxime; Lett, Marie-Claire; Horvatovich, Peter; Gies, Jean-Pierre; Keller, Valerie; Keller, Nicolas; Andre, Philippe

    This study investigates the mechanisms of UV-A (315 to 400 nm) photocatalysis with titanium dioxide (TiO2) applied to the degradation of Escherichia coli and their effects on two key cellular components: lipids and proteins. The impact of TiO2 photocatalysis on E. coli survival was monitored by

  1. Tiamulin resistance mutations in Escherichia coli.

    Science.gov (United States)

    Böck, A; Turnowsky, F; Högenauer, G

    1982-01-01

    Forty "two-step" and 13 "three-step" tiamulin-resistant mutants of Escherichia coli PR11 were isolated and tested for alteration of ribosomal proteins. Mutants with altered ribosomal proteins S10, S19, L3, and L4 were detected. The S19, L3, and L4 mutants were studied in detail. The L3 and L4 mutations did not segregate from the resistance character in transductional crosses and therefore seem to be responsible for the resistance. Extracts of these mutants also exhibited an increased in vitro resistance to tiamulin in the polyuridylic acid and phage R17 RNA-dependent polypeptide synthesis systems, and it was demonstrated that this was a property of the 50S subunit. In the case of the S19 mutant, genetic analysis showed segregation between resistance and the S19 alteration and therefore indicated that mutation of a protein other than S19 was responsible for the resistance phenotype. The isolated ribosomes of the S19, L3, and L4 mutants bound radioactive tiamulin with a considerably reduced strength when compared with those of wild-type cells. The association constants were lower by factors ranging from approximately 20 to 200. When heated in the presence of ammonium chloride, these ribosomes partially regained their avidity for tiamulin. Images PMID:7050084

  2. The effect of an extract from Ganoderma lucidum (reishi) on the labeling of blood constituents with technetium-99m and on the survival of Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Agostinho, Raquel Terra [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Santos Filho, Sebastiao David; Fonseca, Adenilson de Souza da; Bernardo-Filho, Mario [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Inst. de Biologia Roberto Alcantara Gomes. Dept. de Biofisica e Biometria; Missailidis, Sotiris [The Open University, Milton Keynes (United Kingdom). Dept. of Chemistry and Analytical Sciences

    2008-12-15

    This study evaluated effects of an aqueous extract of Ganoderma lucidum (reishi) on the labeling of blood constituents with technetium-99m ({sup 99m}Tc) and on the survival of cultures of Escherichia coli treated with stannous chloride. Blood samples from Wistar rats were treated with reishi extract, radiolabeling procedure was performed, plasma (P), blood cells (BC) and insoluble (IF) and soluble (SF) fractions of P and BC were separated. The radioactivity was counted for the determination of the percentages of radioactivity (%ATI). Cultures of Escherichia coli AB1157 were treated with stannous chloride in the presence and absence of reishi extract. Blood samples and bacterial cultures treated with NaCl 0.9% were used as controls. Data indicated that reishi extract altered significantly (p<0.05) the %ATI of P, BC, IF-P, SF-P, IF-BC and SF-BC, as well as increased the survival of bacterial cultures treated with stannous chloride. Our results suggest that reishi extract could present a redox/chelating action, altering the labeling of blood constituents with {sup 99}mTc and protecting bacterial cultures against oxidative damage induced by stannous chloride. (author)

  3. Deactivation of Escherichia coli by the plasma needle

    International Nuclear Information System (INIS)

    Sladek, R E J; Stoffels, E

    2005-01-01

    In this paper we present a parameter study on deactivation of Escherichia coli (E. coli) by means of a non-thermal plasma (plasma needle). The plasma needle is a small-sized (1 mm) atmospheric glow sustained by radio-frequency excitation. This plasma will be used to disinfect heat-sensitive objects; one of the intended applications is in vivo deactivation of dental bacteria: destruction of plaque and treatment of caries. We use E. coli films plated on agar dishes as a model system to optimize the conditions for bacterial destruction. Plasma power, treatment time and needle-to-sample distance are varied. Plasma treatment of E. coli films results in formation of a bacteria-free void with a size up to 12 mm. 10 4 -10 5 colony forming units are already destroyed after 10 s of treatment. Prolongation of treatment time and usage of high powers do not significantly improve the destruction efficiency: short exposure at low plasma power is sufficient. Furthermore, we study the effects of temperature increase on the survival of E. coli and compare it with thermal effects of the plasma. The population of E. coli heated in a warm water bath starts to decrease at temperatures above 40 deg. C. Sample temperature during plasma treatment has been monitored. The temperature can reach up to 60 deg. C at high plasma powers and short needle-to-sample distances. However, thermal effects cannot account for bacterial destruction at low power conditions. For safe and efficient in vivo disinfection, the sample temperature should be kept low. Thus, plasma power and treatment time should not exceed 150 mW and 60 s, respectively

  4. Deactivation of Escherichia coli by the plasma needle

    Energy Technology Data Exchange (ETDEWEB)

    Sladek, R E J; Stoffels, E [Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2005-06-07

    In this paper we present a parameter study on deactivation of Escherichia coli (E. coli) by means of a non-thermal plasma (plasma needle). The plasma needle is a small-sized (1 mm) atmospheric glow sustained by radio-frequency excitation. This plasma will be used to disinfect heat-sensitive objects; one of the intended applications is in vivo deactivation of dental bacteria: destruction of plaque and treatment of caries. We use E. coli films plated on agar dishes as a model system to optimize the conditions for bacterial destruction. Plasma power, treatment time and needle-to-sample distance are varied. Plasma treatment of E. coli films results in formation of a bacteria-free void with a size up to 12 mm. 10{sup 4}-10{sup 5} colony forming units are already destroyed after 10 s of treatment. Prolongation of treatment time and usage of high powers do not significantly improve the destruction efficiency: short exposure at low plasma power is sufficient. Furthermore, we study the effects of temperature increase on the survival of E. coli and compare it with thermal effects of the plasma. The population of E. coli heated in a warm water bath starts to decrease at temperatures above 40 deg. C. Sample temperature during plasma treatment has been monitored. The temperature can reach up to 60 deg. C at high plasma powers and short needle-to-sample distances. However, thermal effects cannot account for bacterial destruction at low power conditions. For safe and efficient in vivo disinfection, the sample temperature should be kept low. Thus, plasma power and treatment time should not exceed 150 mW and 60 s, respectively.

  5. Biological effects of an aqueous extract of Salix alba on the survival of Escherichia coli AB1157 cultures submitted to the action of stannous chloride

    Directory of Open Access Journals (Sweden)

    RAPHAEL S S SOUZA

    2009-01-01

    Full Text Available Stannous chloride (SnC12 is used in nuclear medicine as a reducing agent to obtain technetium-99m-radiopharmaceuticals. It have been reported that natural products might reduce the genotoxic and cytotoxic effects related to SnC12. This work evaluated the biological effects of an aqueous extract of Salix alba on the survival of Escherichia coli (E. coli AB1157 (wild type cultures submitted to the action of SnC12. E. coli AB1157 cultures (exponential growth phase were collected by centrifugation, washed and resuspended in 0.9%NaCl. Samples were incubated in water bath shaker with: (a SnC12 (25mg/ml, (bSalix alba extract(11.6mg/ml and (cSnC12(25mg/ml + Salix alba extract (11.6mg/ml. Incubation with 0.9% NaCl was also carried out (control. At 60 min intervals, aliquots were withdrawn, diluted, spread onto Petri dishes with solid LB medium and incubated overnight. The colonies formed were counted and the survival fractions calculated. The extract was not able to protect the E. coli cultures against the lesive action of SnC12. The extract also did not interfere with the survival of the cultures. It suggested that the substances present in the Salix alba aqueous extract did not interfere strongly with cellular metabolism and did not alter the survival fractions of E. coli AB 1157. It is speculated that this extract cannot interfere with the generation of free radicals, the possible main agent responsible for SnC12 lesive action.

  6. Effects of High Hydrostatic Pressure on Escherichia coli Ultrastructure, Membrane Integrity and Molecular Composition as Assessed by FTIR Spectroscopy and Microscopic Imaging Techniques

    Directory of Open Access Journals (Sweden)

    María Prieto-Calvo

    2014-12-01

    Full Text Available High hydrostatic pressure (HHP is a novel food processing technology that is considered as an attractive alternative to conventional heat treatments for the preservation of foods, due to its lethal effects on pathogenic and spoilage microorganisms, while causing minor effects on food quality and sensorial attributes. This study is aimed at investigating how HHP treatments at varying intensities in the range 50–900 MPa affect the viability, membrane integrity, ultrastructure and molecular composition of Escherichia coli. Results of membrane integrity tests (measurement of cellular leakage and monitoring of propidium iodide uptake through fluorescence microscopy and ultrastructural observations by transmission electron microscopy demonstrated that HHP gave rise to cellular enlargement, membrane damage or detachment, DNA and protein denaturation and loss of intracellular contents. Fourier-transform infrared (FTIR spectroscopy analyses evidenced minor changes in molecular composition in response to high pressures, which were mostly observed on the spectral region w4 (1200–900 cm−1, mainly informative of carbohydrates and polysaccharides of the cell wall. These findings suggest that exposure of E. coli cells to HHP causes alterations in their physical integrity while producing minor modifications in biochemical cellular composition. The current study increases the knowledge on the mechanisms of E. coli inactivation by HHP and provides valuable information for the design of more effective food preservation regimes based on the integration of mild HHP in combination with other food preservation strategies into a multi-target hurdle technology approach.

  7. Effects of high hydrostatic pressure on Escherichia coli ultrastructure, membrane integrity and molecular composition as assessed by FTIR spectroscopy and microscopic imaging techniques.

    Science.gov (United States)

    Prieto-Calvo, María; Prieto, Miguel; López, Mercedes; Alvarez-Ordóñez, Avelino

    2014-12-18

    High hydrostatic pressure (HHP) is a novel food processing technology that is considered as an attractive alternative to conventional heat treatments for the preservation of foods, due to its lethal effects on pathogenic and spoilage microorganisms, while causing minor effects on food quality and sensorial attributes. This study is aimed at investigating how HHP treatments at varying intensities in the range 50-900 MPa affect the viability, membrane integrity, ultrastructure and molecular composition of Escherichia coli. Results of membrane integrity tests (measurement of cellular leakage and monitoring of propidium iodide uptake through fluorescence microscopy) and ultrastructural observations by transmission electron microscopy demonstrated that HHP gave rise to cellular enlargement, membrane damage or detachment, DNA and protein denaturation and loss of intracellular contents. Fourier-transform infrared (FTIR) spectroscopy analyses evidenced minor changes in molecular composition in response to high pressures, which were mostly observed on the spectral region w4 (1200-900 cm-1), mainly informative of carbohydrates and polysaccharides of the cell wall. These findings suggest that exposure of E. coli cells to HHP causes alterations in their physical integrity while producing minor modifications in biochemical cellular composition. The current study increases the knowledge on the mechanisms of E. coli inactivation by HHP and provides valuable information for the design of more effective food preservation regimes based on the integration of mild HHP in combination with other food preservation strategies into a multi-target hurdle technology approach.

  8. Changes in Escherichia coli resistance to co-trimoxazole in ...

    African Journals Online (AJOL)

    In Thyolo district, Malawi, an operational research study is being conducted on the efficacy and feasibility of co-trimoxazole prophylaxis in preventing deaths in HIV-positive patients with tuberculosis (TB). A series of cross-sectional studies were carried out to determine i) whether faecal Escherichia coli (E.coli) resistance to ...

  9. Escherichia coli growth modeling using neural network | Shamsudin ...

    African Journals Online (AJOL)

    technique that has the ability to predict with efficient and good performance. Using NARX, a highly accurate model was developed to predict the growth of Escherichia coli (E. coli) based on pH water parameter. The multiparameter portable sensor and spectrophotometer data were used to build and train the neural network.

  10. Growth modeling of uropathogenic Escherichia coli in ground chicken meat

    Science.gov (United States)

    Extraintestinal Pathogenic Escherichia coli (ExPEC), including Uropathogenic E. coli (UPEC), are common contaminants in poultry meat, and are a major pathogen associated with inflammatory bowel disease, ulcerative colitis, sepsis, and urinary tract infections. The purpose of this study was to determ...

  11. Antimicrobial susceptibilities of avian Escherichia coli isolates in ...

    African Journals Online (AJOL)

    Colibacillosis is a poultry disease of economic importance in Iran and all around the world. The aim of this study is to test the antibiotic sensitivity of Escherichia coli strains which were isolated in Tabriz. A total of 100 E. coli strains isolated from avian colibacillosis of 50 farms from 2008 to 2009 in Tabriz, were investigated for ...

  12. Prevalence of Aeromonas species and Escherichia coli in stool ...

    African Journals Online (AJOL)

    Background: Diarrhoea is one of the main causes of mortality and morbidity in childhood. Bacterial diarrhoea is a common disorder. Aeromonas species and Escherichia coli (E. coli) are some of the aetiological agents associated with diarrhoea in children. Objective: To determine the prevalence of Aeromonas species and ...

  13. Adsorption of Escherichia coli Using Bone Char | Rezaee | Journal ...

    African Journals Online (AJOL)

    The aim of study was providing a novel adsorbent for the removal of Escherichia coli (E.coli) as a microbial model from contaminated air especially in hospital units using bone char (BC). The BC was prepared from cattle animal bone by pyrolysis in a furnace at 450°C for 2 h. The characteristics of BC have been determined ...

  14. Draft Genome Sequence of Escherichia coli K-12 (ATCC 10798)

    OpenAIRE

    Dimitrova, Daniela; Engelbrecht, Kathleen C.; Putonti, Catherine; Koenig, David W.; Wolfe, Alan J.

    2017-01-01

    ABSTRACT Here, we present the draft genome sequence of Escherichia coli ATCC 10798. E.?coli ATCC 10798 is a K-12 strain, one of the most well-studied model microorganisms. The size of the genome was 4,685,496?bp, with a G+C content of 50.70%. This assembly consists of 62 contigs and the F plasmid.

  15. Impact of cranberry on Escherichia coli cellular surface characteristics

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  16. Sedimentation and gravitational instability of Escherichia coli Suspension

    Science.gov (United States)

    Salin, Dominique; Douarche, Carine

    2017-11-01

    The successive runs and tumbles of Escherichia coli bacteria provide an active matter suspension of rod-like particles with a large swimming, Brownian like, diffusion. As opposed to inactive elongated particles, this diffusion prevents clustering of the particles and hence instability in the gravity field. We measure the time dependent E . coli concentration profile during their sedimentation. After some hours, due to the dioxygen consumption, a motile / non-motile front forms leading to a Rayleigh-Taylor type gravitational instability. Analysing both sedimentation and instability in the framework of active particle suspensions, we can measure the relevant bacteria hydrodynamic characteristics such as its single particle sedimentation velocity and its hindrance volume. Comparing these quantities to the ones of equivalent passive particles (ellipsoid, rod) we tentatively infer the effective shape and size of the bacteria involved in its buoyancy induced advection and diffusion. Laboratoire FAST University Paris Saclay France.

  17. Impact of antibiotic restriction on resistance levels of Escherichia coli

    DEFF Research Database (Denmark)

    Boel, Jonas; Andreasen, Viggo; Jarløv, Jens Otto

    2016-01-01

    as a retrospective controlled interrupted time series (ITS) at two university teaching hospitals, intervention and control, with 736 and 552 beds, respectively. The study period was between January 2008 and September 2014. We used ITS analysis to determine significant changes in antibiotic use and resistance levels......% CI -177, -126)] and fluoroquinolones [-44.5 DDDs/1000 bed-days (95% CI -58.9, -30.1)]. Resistance of E. coli showed a significant change in slope for cefuroxime [-0.13 percentage points/month (95% CI -0.21, -0.057)] and ciprofloxacin [-0.15 percentage points/month (95% CI -0.26, -0.038)]. CONCLUSIONS......OBJECTIVES: We evaluated the effect of an antibiotic stewardship programme (ASP) on the use of antibiotics and resistance levels of Escherichia coli using a method that allowed direct comparison between an intervention hospital and a control hospital. METHODS: The study was conducted...

  18. MUTATIONAL SYNERGISM BETWEEN RADIATIONS AND METHYLATED PURINES IN ESCHERICHIA COLI

    Science.gov (United States)

    Doneson, Ira N.; Shankel, Delbert M.

    1964-01-01

    Doneson, Ira N. (University of Kansas, Lawrence), and Delbert M. Shankel. Mutational synergism between radiations and methylalted purines in Escherichia coli. J. Bacteriol. 87:61–67. 1964.—A synergistic mutational effect was demonstrated between low doses of ultraviolet light and the methylated purines caffeine, theophylline, and theobromine. Caffeine produced the greatest effect and theobromine the least effect. The magnitude of the synergism was inversely related to the ultraviolet dosage. A large percentage of the synergistic effect could be “photoprevented” by exposure of the ultraviolet-treated cells to white light prior to exposure to the analogues. The consequence of the combined treatment occurred only when the chemical treatment followed the ultraviolet treatment. Furthermore, it was necessary to administer the chemical treatment soon after the ultraviolet treatment or the mutants were “lost.” When cells were treated with low dosages of ultraviolet light and of X irradiation (X ray), the result was merely additive, and combinations of X ray and chemical treatment yielded no synergism. Synchronous growth studies indicated that a particular growth stage of the organisms was most susceptible to the synergistic effect. The mutation studied was that of Escherichia coli B/r to high-level streptomycin resistance. PMID:14102875

  19. Near-ultraviolet radiation-induced lipid peroxidation and membrane effects in Escherichia coli and human skin fibroblasts

    International Nuclear Information System (INIS)

    Chamberlain, J.

    1987-01-01

    The first part of this thesis examines the response of an unsaturated fatty acid auxotroph, Escherichia coli K1060 to broad-band near-UV radiation. Sensitivity, lipid peroxidation and leakage of rubidium from irradiated cells were found to increase with increasing unsaturation of membrane fatty acids. The involvement of singlet oxygen was implicated by an increase in sensitivity, lipid peroxidation and leakage of rubidium following irradiation in deuterium oxide. Some factors influencing survival following irradiation were investigated, where lower growth rates were shown to enhance survival. In the second part, the study was extended to human fibroblasts where a normal human skin fibroblast strain, GM730 and a strain derived from an actinic reticuloid patient, AR6LO, are compared. Lipid peroxidation was measured in both cell lines following broad-band near-UV irradiation. Membrane activity, as assessed by the pinocytic uptake of 14 C-sucrose and its subsequent release from the cell, was measured. Near-UV irradiation was found to increase such activity in both strains. Vitamin E and Trolox-C were found to decrease this response in AR6LO but not GM730 cells. The final part consists of preliminary investigations into the near-UV induced peroxidation of fatty acids and liposomes, and the subsequent increase in the level of hydroperoxides in the hours following irradiation. (author)

  20. Effect of Neem (Azadirachta indica on the Survival of Escherichia coli O157:H7 in Dairy Manure

    Directory of Open Access Journals (Sweden)

    Subbarao V. Ravva

    2015-07-01

    Full Text Available Escherichia coli O157:H7 (EcO157 shed in cattle manure can survive for extended periods of time and intervention strategies to control this pathogen at the source are critical as produce crops are often grown in proximity to animal raising operations. This study evaluated whether neem (Azadirachta indica, known for its antimicrobial and insecticidal properties, can be used to amend manure to control EcO157. The influence of neem materials (leaf, bark, and oil on the survival of an apple juice outbreak strain of EcO157 in dairy manure was monitored. Neem leaf and bark supplements eliminated the pathogen in less than 10 d with a D-value (days for 90% elimination of 1.3 d. In contrast, nearly 4 log CFU EcO157/g remained after 10 d in neem-free manure control. The ethyl acetate extractable fraction of neem leaves was inhibitory to the growth of EcO157 in LB broth. Azadirachtin, a neem product with insect antifeedant properties, failed to inhibit EcO157. Application of inexpensive neem supplements to control pathogens in manure and possibly in produce fields may be an option for controlling the transfer of foodborne pathogens from farm to fork.

  1. Effect of cra gene knockout together with edd and iclR genes knockout on the metabolism in Escherichia coli.

    Science.gov (United States)

    Sarkar, Dayanidhi; Siddiquee, Khandaker Al Zaid; Araúzo-Bravo, Marcos J; Oba, Takahiro; Shimizu, Kazuyuki

    2008-11-01

    To elucidate the physiological adaptation of Escherichia coli due to cra gene knockout, a total of 3,911 gene expressions were investigated by DNA microarray for continuous culture. About 50 genes were differentially regulated for the cra mutant. TCA cycle and glyoxylate shunt were down-regulated, while pentose phosphate (PP) pathway and Entner Doudoroff (ED) pathway were up-regulated in the cra mutant. The glucose uptake rate and the acetate production rate were increased with less acetate consumption for the cra mutant. To identify the genes controlled by Cra protein, the Cra recognition weight matrix from foot-printing data was developed and used to scan the whole genome. Several new Cra-binding sites were found, and some of the result was consistent with the DNA microarray data. The ED pathway was active in the cra mutant; we constructed cra.edd double genes knockout mutant to block this pathway, where the acetate overflowed due to the down-regulation of aceA,B and icd gene expressions. Then we further constructed cra.edd.iclR triple genes knockout mutant to direct the carbon flow through the glyoxylate pathway. The cra.edd.iclR mutant showed the least acetate production, resulting in the highest cell yield together with the activation of the glycolysis pathway, but the glucose consumption rate could not be improved.

  2. Studying the effect of administration route and treatment dose on the selection of enrofloxacin resistance in commensal Escherichia coli in broilers.

    Science.gov (United States)

    Chantziaras, Ilias; Smet, Annemieke; Haesebrouck, Freddy; Boyen, Filip; Dewulf, Jeroen

    2017-07-01

    Factors potentially contributing to fluoroquinolone resistance selection in commensal Escherichia coli strains in poultry were studied through a series of in vivo experiments. The effect of the initial prevalence of enrofloxacin resistance in the E. coli gut microbiota, effect of the bacterial fitness of the enrofloxacin-resistant strain and effect of treatment with enrofloxacin (effect of dose and effect of route of administration) were assessed. Four in vivo studies with broiler chickens were performed. Right after hatching, the chicks were inoculated with either a bacteriologically fit or a bacteriologically non-fit fluoroquinolone-resistant strain as either a minority or the majority of the total E. coli population. Six days later, the chicks were treated for three consecutive days either orally or parenterally and using three different doses (under-, correct- and over-dose) of enrofloxacin. The faecal shedding of E. coli strains was quantified by plating on agar plates either supplemented or not supplemented with enrofloxacin. Linear mixed models were used to assess the effect of the aforementioned variables on the selection of enrofloxacin resistance. The factors that significantly contributed were treatment ( P  <   0.001), bacterial fitness of the resistant donor strain ( P  <   0.001), administration route ( P  =   0.052) and interactions between bacterial fitness and administration route ( P  <   0.001). In the currently used models, fluoroquinolone resistance selection was influenced by treatment, bacterial fitness of the inoculation strain and administration route. The use of oral treatment seems to select more for fluoroquinolone resistance, particularly in the model where a non-fit strain was used for inoculation. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Findings of Escherichia coli and Enterococcus spp. in homemade cheese

    Directory of Open Access Journals (Sweden)

    Tambur Zoran

    2007-01-01

    Full Text Available During the period from February until March 2004, 108 samples of soft cheese originating from markets of Pancevo, Subotica and Belgrade were examined. Microbiological analyses of the cheese samples to the presence of Escherichia coli was performed using methods described in the Regulations on methods for performing microbiological analyses and super analyses of consumer articles, while the presence of bacteria Enteroccocus spp. was performed on the dexter agar. From 108 samples of soft cheese from the territories of Pancevo, Belgrade and Subotica were isolated: Enterococcus spp. from 96% and Escherichia coli from 69%, cheese samples. Verocytotoxic E.coli was not isolated from any of the taken cheese samples.

  4. Difference in melting profiles of gamma irradiated DNA from chicken erythrocytes and from Escherichia coli B/r

    International Nuclear Information System (INIS)

    Kopff, J.; Miller, G.; Leyko, W.

    1977-01-01

    Effects of gamma irradiation on melting curves of DNA from chicken erythrocytes and Escherichia coli B/r were compared. Considerable changes, following gamma irradiation in the case of chicken erythrocytes DNA and no changes in the case of DNA from Escherichia coli B/r were observed. To explain the lack of changes in gamma irradiated samples of DNA from Escherichia coli B/r it was assumed that the original effects of irradiation were obscured by the process of renaturation of DNA. To exclude the above mentioned effect, examination of gamma irradiated DNA from Escherichia coli B/r was carried out with the addition of formaldehyde immediately after irradiation of the sample. Using this procedure changes of melting profiles of DNA from Escherichia coli B/r were demonstrated. (author)

  5. Multiplex polymerase chain reaction for identification of Escherichia coli, Escherichia albertii and Escherichia fergusonii.

    Science.gov (United States)

    Lindsey, Rebecca L; Garcia-Toledo, L; Fasulo, D; Gladney, L M; Strockbine, N

    2017-09-01

    Escherichia coli, Escherichia albertii, and Escherichia fergusonii are closely related bacteria that can cause illness in humans, such as bacteremia, urinary tract infections and diarrhea. Current identification strategies for these three species vary in complexity and typically rely on the use of multiple phenotypic and genetic tests. To facilitate their rapid identification, we developed a multiplex PCR assay targeting conserved, species-specific genes. We used the Daydreamer™ (Pattern Genomics, USA) software platform to concurrently analyze whole genome sequence assemblies (WGS) from 150 Enterobacteriaceae genomes (107 E. coli, 5 Shigella spp., 21 E. albertii, 12 E. fergusonii and 5 other species) and design primers for the following species-specific regions: a 212bp region of the cyclic di-GMP regulator gene (cdgR, AW869_22935 from genome K-12 MG1655, CP014225) for E. coli/Shigella; a 393bp region of the DNA-binding transcriptional activator of cysteine biosynthesis gene (EAKF1_ch4033 from genome KF1, CP007025) for E. albertii; and a 575bp region of the palmitoleoyl-acyl carrier protein (ACP)-dependent acyltransferase (EFER_0790 from genome ATCC 35469, CU928158) for E. fergusonii. We incorporated the species-specific primers into a conventional multiplex PCR assay and assessed its performance with a collection of 97 Enterobacteriaceae strains. The assay was 100% sensitive and specific for detecting the expected species and offers a quick and accurate strategy for identifying E. coli, E. albertii, and E. fergusonii in either a single reaction or by in silico PCR with sequence assemblies. Published by Elsevier B.V.

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  7. Succinic acid production by escherichia coli under anaerobic fermentation

    International Nuclear Information System (INIS)

    El Shafey, H.M.; Meleigy, S.A.

    2009-01-01

    The effect of alteration of growth conditions, addition of different sodium salts, and irradiation by gamma rays on succinic acid production by E. coli was studied. Twenty one isolates were obtained from buffalo's rumen, and anaerobic screening of the isolated bacterial strains showed the abilities of seventeen strains to produce succinic acid. The two bacterial strains having highest succinic acid production were identified as escherichia coli SP9 and SP16, and were selected for further studies. Results showed that growth conditions yielded highest succinic acid production for the two isolates were: 72 hours incubation, 37 degree c incubation temperature, initial ph of the fermentation medium 6.0,and 3% (v/v)inoculum size. Addition of 5 mm of nine different sodium salts to the fermentation medium showed stimulating effect on succinic acid production of the nine tried sodium salts, sodium carbonate was found to have the highest enhancing effect, especially if used at 15 mm concentration. Gamma irradiation doses tried were in the range of (0.25-1.50 kGy). An enhancing effect on succinic acid production was shown in the range of 0.25-0.75 kGy with a maximal production at 0.75 kGy (giving 8.36% increase) for e.coli SP9, and in the range of 0.25-1.00 kGy with a maximal production at 1.0 kGy (7.60% increase) for e.coli SP16. higher gamma doses led to a decrease in the enhancing effect. An overall increase in the succinic acid yield of 79.45% and 94.26% for e. coli SP9 and SP16, respectively, was achieved in implicating all optimized factors for succinic acid production in one time

  8. Annual Surveillance Summary: Escherichia coli (E. coli) Infections in the Military Health System (MHS), 2015

    Science.gov (United States)

    2017-03-01

    Annual Surveillance Summary: Escherichia coli ( E . coli ) Infections in the Military Health System (MHS...or position of the Department of the Navy, Department of Defense, nor the U.S. Government. i i E . coli in the MHS: Annual Summary 2015 Prepared...March 2017 EpiData Center Department NMCPHC-EDC-TR-187-2017 ii ii E . coli in the MHS: Annual Summary 2015 Prepared March 2017 EpiData

  9. Effects of glycerol upon the biological actions of near-ultraviolet light: spectra and concentration dependence for transforming DNA and for Escherichia coli B/r

    International Nuclear Information System (INIS)

    Peak, J.G.; Peak, M.J.; Foote, C.S.

    1982-01-01

    The concentration dependence for the protection of isolated transforming DNA and Escherichia coli by glycerol against 365-nm monochromatic near-ultraviolet light (UV) was measured. Glycerol protection saturates at a concentration of about 0.1 M for DNA and 1.0 M for E. coli. Action spectra for glycerol protection of transforming DNA (tryptophan and histidine markers) are similar to those obtained previously for diazobicyclo[2.2.2.]octane (DABCO) protection, with protection reaching a maximum near 350-nm UV and decreasing rapidly at wavelengths above and below 350 nm. However, glycerol protects against near-UV about twice as efficiently as DABCO. The action spectrum for protection of E. coli by glycerol against the lethal effects of near-UV was not the same as the spectrum for DNA since glycerol sensitized the cells, but not the DNA, at wavelengths longer than about 380 nm. A possible role of hydroxyl or other radicals was supported by the observation that benzoate also protected DNA against inactivation by 334-nm UV. (author)

  10. The effect of bacterial environmental and metabolic stresses on a laser-induced breakdown spectroscopy (LIBS) based identification of Escherichia coli and Streptococcus viridans.

    Science.gov (United States)

    Mohaidat, Qassem; Palchaudhuri, Sunil; Rehse, Steven J

    2011-04-01

    In this paper we investigate the effect that adverse environmental and metabolic stresses have on the laser-induced breakdown spectroscopy (LIBS) identification of bacterial specimens. Single-pulse LIBS spectra were acquired from a non-pathogenic strain of Escherichia coli cultured in two different nutrient media: a trypticase soy agar and a MacConkey agar with a 0.01% concentration of deoxycholate. A chemometric discriminant function analysis showed that the LIBS spectra acquired from bacteria grown in these two media were indistinguishable and easily discriminated from spectra acquired from two other non-pathogenic E. coli strains. LIBS spectra were obtained from specimens of a nonpathogenic E. coli strain and an avirulent derivative of the pathogen Streptococcus viridans in three different metabolic situations: live bacteria reproducing in the log-phase, bacteria inactivated on an abiotic surface by exposure to bactericidal ultraviolet irradiation, and bacteria killed via autoclaving. All bacteria were correctly identified regardless of their metabolic state. This successful identification suggests the possibility of testing specimens that have been rendered safe for handling prior to LIBS identification. This would greatly enhance personnel safety and lower the cost of a LIBS-based diagnostic test. LIBS spectra were obtained from pathogenic and non-pathogenic bacteria that were deprived of nutrition for a period of time ranging from one day to nine days by deposition on an abiotic surface at room temperature. All specimens were successfully classified by species regardless of the duration of nutrient deprivation. © 2011 Society for Applied Spectroscopy

  11. The Effects of Sugars on the Biofilm Formation of Escherichia coli 185p on Stainless Steel and Polyethylene Terephthalate Surfaces in a Laboratory Model.

    Science.gov (United States)

    Khangholi, Mahdi; Jamalli, Ailar

    2016-09-01

    Bacteria utilize various methods in order to live in protection from adverse environmental conditions. One such method involves biofilm formation; however, this formation is dependent on many factors. The type and concentration of substances such as sugars that are present in an environment can be effective facilitators of biofilm formation. First, the physico-chemical properties of the bacteria and the target surface were studied via the MATS and contact angle measurement methods. Additionally, adhesion to different surfaces in the presence of various concentrations of sugars was compared in order to evaluate the effect of these factors on the biofilm formation of Escherichia coli , which represents a major food contaminant . Results showed that the presence of sugars has no effect on the bacterial growth rate; all three concentrations of sugars were hydrophilic and demonstrated a high affinity toward binding to the surfaces. The impact of sugars and other factors on biofilm formation can vary depending on the type of bacteria present.

  12. [Effect of eicosapentaenoic acid on mRNA expression of tight junction protein ZO-1 in intestinal epithelial cells after Escherichia coli LF82 infection].

    Science.gov (United States)

    Hao, Li-Jun; Lin, Yan; Zhang, Wei; Tian, Jiao; Wang, Ya; Chen, Peng-De; Hu, Chong-Kang; Zeng, Ling-Chao; Yang, Jie; Wang, Bao-Xi; Jiang, Xun

    2017-06-01

    To investigate the change in the expression of tight junction protein ZO-1 in intestinal epithelial cells (Caco-2 cells) and the protective effect of eicosapentaenoic acid (EPA) after adherent-invasive Escherichia coli (E.coli) LF82 infection. The Caco-2 cell line was used to establish an in vitro model of tight junction of intestinal epithelial cells. Caco-2 cells were divided into EPA treatment groups (0, 25, 50, 100, and 200 μmol/L EPA) and EPA (0, 25, 50, 100, and 200 μmol/L EPA)+E.coli LF82 treatment (0, 6, and 12 hours) groups. A microscope was used to observe the morphological characteristics of the cells. MTT assay was used to determine the cell growth curve. The activity of alkaline phosphatase (ALP) at both sides of the cell membrane was compared to evaluate the Caco-2 cell model. MTT assay and flow cytometry were used to investigate the effects of different concentrations of EPA on the survival rate and apoptosis rate of Caco-2 cells. RT-qPCR was used to measure the mRNA expression of ZO-1 in Caco-2 cells after EPA and/or E.coli LF82 treatment. ELISA was used to measure the change in the level of tumor necrosis factor-α (TNF-α) in culture supernatant. After EPA treatment (25 and 50 μmol/L), the proliferation of Caco-2 cells was induced in a dose-dependent manner. The survival rates of the cells were significantly higher than those in the control group (PE.coli LF82 treatment groups had decreasing mRNA expression of ZO-1 in Caco-2 cells over the time of treatment and had significantly lower mRNA expression of ZO-1 than the untreated group (PE.coli LF82 and 25 or 50 μmol/L EPA for 6 or 12 hours showed an increase in the mRNA expression of ZO-1 with the increasing concentration of EPA, as well as significantly higher mRNA expression of ZO-1 than the Caco-2 cells treated with E.coli LF82 alone (PE.coli LF82 alone for 6 or 12 hours had increasing secretion of TNF-α over the time of treatment and had significantly higher secretion than the untreated

  13. Environmental Escherichia coli: Ecology and public health implications - A review

    Science.gov (United States)

    Jang, Jeonghwan; Hur, Hor-Gil; Sadowsky, Michael J.; Byappanahalli, Muruleedhara; Yan, Tao; Ishii, Satoshi

    2017-01-01

    Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae. The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through feces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent fecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extra-intestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a fecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics provide the diversity and complexity of E. coli strains in various environments, affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments in regards to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia. The impact of environmental E. coli on water quality and public health is also discussed.

  14. Effects of the umuC36 mutation on ultraviolet-radiation-induced base-change and frameshift mutations in Escherichia coli

    International Nuclear Information System (INIS)

    Kato, T.; Nakano, E.

    1981-01-01

    The effects of the umuC36 mutation on the induction of base-change and frameshift mutations were studied. An active umuC gene was necessary in either the uvr + or uvr - strains of Escherichia coli K12 for UV- and X-ray-induced mutations to His + , ColE and Spc, which are presumably base-change mutations, but it was not essential for ethyl methanesulphonate or N-methyl-N'-nitro-N-nitrosoguanidine-induced His + mutations. In contrast, only 1 out of 13 trp - frameshift mutations examined was UV reversible, and the process of mutagenesis was umuC + -dependent, whereas a potent frameshift mutagen, ICR191, effectively induced Trp + mutations in most of the strains regardless of the umu + or umuC genetic background. These results suggest that base substitutions are a major mutational type derived from the umuC + -dependent pathway of error-prone repair. (orig.)

  15. Current pathogenic Escherichia coli foodborne outbreak cases and therapy development.

    Science.gov (United States)

    Yang, Shih-Chun; Lin, Chih-Hung; Aljuffali, Ibrahim A; Fang, Jia-You

    2017-08-01

    Food contamination by pathogenic microorganisms has been a serious public health problem and a cause of huge economic losses worldwide. Foodborne pathogenic Escherichia coli (E. coli) contamination, such as that with E. coli O157 and O104, is very common, even in developed countries. Bacterial contamination may occur during any of the steps in the farm-to-table continuum from environmental, animal, or human sources and cause foodborne illness. To understand the causes of the foodborne outbreaks by E. coli and food-contamination prevention measures, we collected and investigated the past 10 years' worldwide reports of foodborne E. coli contamination cases. In the first half of this review article, we introduce the infection and symptoms of five major foodborne diarrheagenic E. coli pathotypes: enteropathogenic E. coli (EPEC), Shiga toxin-producing E. coli/enterohemorrhagic E. coli (STEC/EHEC), Shigella/enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), and enterotoxigenic E. coli (ETEC). In the second half of this review article, we introduce the foodborne outbreak cases caused by E. coli in natural foods and food products. Finally, we discuss current developments that can be applied to control and prevent bacterial food contamination.

  16. Effect of aqueous media on the copper-ion-mediated phototoxicity of CuO nanoparticles toward green fluorescent protein-expressing Escherichia coli.

    Science.gov (United States)

    Shang, Enxiang; Li, Yang; Niu, Junfeng; Guo, Huiyuan; Zhou, Yijing; Liu, Han; Zhang, Xinqi

    2015-12-01

    Quantitative comparison of different aqueous media on the phototoxicity of copper oxide nanoparticles (CuO NPs) is crucial for understanding their ecological effects. In this study, the phototoxicity of CuO NPs toward the green fluorescent protein-expressing Escherichia coli (GFP-E. coli) under UV irradiation (365 nm) was investigated in Luria-Bertani medium (LB), NaCl solution, deionized water (DI) and phosphate-buffered saline (PBS). The phototoxicity of CuO NPs toward GFP-E. coli decreased in the order of DI>NaCl>PBS>LB because of different released concentrations of Cu(2+). The 3h released Cu(2+) concentrations by 10mg/L CuO NPs in DI water, NaCl solution, LB medium, and PBS were 1946.3 ± 75.6, 1242.5 ± 47.6, 1023.4 ± 41.2, and 1162.1 ± 41.9 μg/L, respectively. Transmission electron microscope and laser scanning confocal microscope images of E. coli exposed to CuO NPs demonstrated that the released Cu(2+) resulted in fragmentation of bacterial cell walls, leakage of intracellular components, and finally death of bacteria in four media after UV light irradiation. In each medium, the bacterial mortality rate logarithmically increased with the releasing concentrations of Cu(2+) by CuO NPs (R(2)>0.90) exposed to 3h UV light. This study highlights the importance of taking into consideration of water chemistry when the phototoxicity of CuO NPs is assessed in nanotoxicity research. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Human Meningitis-Associated Escherichia coli

    Science.gov (United States)

    KIM, KWANG SIK

    2016-01-01

    E. coli is the most common Gram-negative bacillary organism causing meningitis and E. coli meningitis continues to be an important cause of mortality and morbidity throughout the world. Our incomplete knowledge of its pathogenesis contributes to such mortality and morbidity. Recent reports of E. coli strains producing CTX-M-type or TEM-type extended-spectrum β-lactamases create a challenge. Studies using in vitro and in vivo models of the blood-brain barrier have shown that E. coli meningitis follows a high-degree of bacteremia and invasion of the blood-brain barrier. E. coli invasion of the blood-brain barrier, the essentials step in the development of E. coli meningitis, requires specific microbial and host factors as well as microbe- and host-specific signaling molecules. Blockade of such microbial and host factors contributing to E. coli invasion of the blood-brain barrier is shown to be efficient in preventing E. coli penetration into the brain. The basis for requiring a high-degree of bacteremia for E. coli penetration of the blood-brain barrier, however, remains unclear. Continued investigation on the microbial and host factors contributing to a high-degree of bacteremia and E. coli invasion of the blood-brain barrier is likely to identify new targets for prevention and therapy of E. coli meningitis. PMID:27223820

  18. Quantifying the combined effects of pronase and benzalkonium chloride in removing late-stage Listeria monocytogenes-Escherichia coli dual-species biofilms.

    Science.gov (United States)

    Rodríguez-López, Pedro; Puga, Carmen H; Orgaz, Belén; Cabo, Marta L

    2017-09-01

    This work presents the assessment of the effectivity of a pronase (PRN)-benzalkonium chloride (BAC) sequential treatment in removing Listeria monocytogenes-Escherichia coli dual-species biofilms grown on stainless steel (SS) using fluorescence microscopy and plate count assays. The effects of PRN-BAC on the occupied area (OA) by undamaged cells in 168 h dual-species samples were determined using a first-order factorial design. Empirical equations significantly (r 2 = 0.927) described a negative individual effect of BAC and a negative interactive effect of PRN-BAC achieving OA reductions up to 46%. After treatment, high numbers of remaining attached and released viable and cultivable E. coli cells were detected in PRN-BAC combinations when low BAC concentrations were used. Therefore, at appropriate BAC doses, in addition to biofilm removal, sequential application of PRN and BAC represents an appealing strategy for pathogen control on SS surfaces while hindering the dispersion of live cells into the environment.

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

    Directory of Open Access Journals (Sweden)

    Tammy eGonzalez

    2015-10-01

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

  20. Teriyaki sauce with carvacrol or thymol effectively controls Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, and indigenous flora in marinated beef and marinade.

    Science.gov (United States)

    Moon, Hyeree; Kim, Nam Hee; Kim, Soon Han; Kim, Younghoon; Ryu, Jee Hoon; Rhee, Min Suk

    2017-07-01

    An effective bactericidal cold-marinating method for beef products is described, exploiting the synergism between soy sauce and natural compounds (carvacrol, CV or thymol, TM) to reduce microbiological risks. Beef slices inoculated with Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium (3.1-3.5logCFU/g) were marinated in a teriyaki sauce with or without CV and TM (0.3 and 0.5%). After 1, 3, and 7days at 4°C, indigenous microflora population, color, lipid oxidation, marinade uptake, and pH of marinated beef and leftover marinade samples were examined. Teriyaki sauce alone did not reduce or inhibit any of the target pathogens or indigenous bacteria, while 0.5% CV- or TM-containing teriyaki sauce inactivated all inocula without recovery within 7days (p0.05). Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Radiosensitization of Escherichia coli and Salmonella typhi in presence of active compounds

    International Nuclear Information System (INIS)

    Lacroix, M.; Chiasson, F.; Borsa, J.; Ouattara, B.

    2004-01-01

    The radiosensitization of Escherichia coli and Salmonella typhi in ground beef was evaluated in the presence of 18 active compounds. Medium fat ground beef (23% fat) was inoculated with E. coli or S. typhi and each active compound was added separately at various concentrations. For E. coli, the most efficient compounds were trans-cinnamaldehyde, thymol and thyme. For S. typhi, the most efficient compounds was trans-cinnamaldehyde, carvacrol and thymol. The addition of tetrasodium pyrophosphate, carvacrol and ascorbic acid had no effect on the irradiation sensitivity of E. coli. For S. typhi, only ascorbic acid had no effect

  2. Radiosensitization of Escherichia coli and Salmonella typhi in presence of active compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lacroix, M. E-mail: monique.lacroix@inrs-iaf.uquebec.ca; Chiasson, F.; Borsa, J.; Ouattara, B

    2004-10-01

    The radiosensitization of Escherichia coli and Salmonella typhi in ground beef was evaluated in the presence of 18 active compounds. Medium fat ground beef (23% fat) was inoculated with E. coli or S. typhi and each active compound was added separately at various concentrations. For E. coli, the most efficient compounds were trans-cinnamaldehyde, thymol and thyme. For S. typhi, the most efficient compounds was trans-cinnamaldehyde, carvacrol and thymol. The addition of tetrasodium pyrophosphate, carvacrol and ascorbic acid had no effect on the irradiation sensitivity of E. coli. For S. typhi, only ascorbic acid had no effect.

  3. Genetic Control of the Secondary Modification of Deoxyribonucleic Acid in Escherichia coli1

    Science.gov (United States)

    Mamelak, Linda; Boyer, Herbert W.

    1970-01-01

    The wild-type restriction and modification alleles of Escherichia coli K-12 and B were found to have no measurable effect on the patterns of methylated bases in the deoxyribonucleic acid (DNA) of these strains. The genetic region controlling the methylation of cytosine in E. coli K-12 was mapped close to his, and the presence or absence of this gene in E. coli B or E. coli K had no effect on the restriction and modification properties of these strains. Thus, only a few of the methylated bases in the DNA of these strains are involved in host modification, and the biological role of the remainder remains obscure. PMID:4919756

  4. Effects of sodium arsenite on the survival of UV-irradiated Escherichia coli: inhibition of a recA-dependent function

    Energy Technology Data Exchange (ETDEWEB)

    Rossman, T; Meyn, M S; Troll, W [New York Univ., N.Y. (USA). Dept. of Environmental Medicine

    1975-11-01

    Epidemiological studies and clinical observations suggesting potential hazards of arsenic compounds in increasing the incidence of cancer have been in complete contradiction with experimental findings in animals. Because of the predominance of skin cancers in the epidemiological reports, it was decided to investigate the possibility that arsenic compounds might interfere with DNA repair. Using Escherichia coli as a test system, it is shown that this is indeed the case. Sodium arsenite, at concentrations of 0.1mM and higher, decreases the survival of ultraviolet-irradiated E.coli WP2, a strain which possesses the full complement of repair genes. The effect of the arsenite increases with increasing ultraviolet dose. Similar results were obtained with the excision repair deficient strains WWP2 (uvrA) and WP6(polA). Sodium arsenite had no effect on the survival of recA mutant, WP10. Survival of ultraviolet-irradiated WP5(exrA) was enhanced by sodium arsenite, the effect being greatest at low ultraviolet doses. It is postulated that arsenite inhibits a recA-dependent step in DNA repair. To account for the increased survival of the exrA mutant, it is suggested that in the absence of the exr/sup +/ gene, the arsenite-sensitive recA-dependent function is deleterious. The ability of arsenite to inhibit DNA repair may account for the clinical and epidemiological reports linking arsenicals with an increased incidence of cancer.

  5. Effect of bacteriocin-producing lactobacilli on the survival of Escherichia coli and Listeria in a dynamic model of the stomach and the small intestine

    NARCIS (Netherlands)

    Gänzle, M.G.; Hertel, C.; Vossen, J.M.B.M. van der; Hammes, W.P.

    1999-01-01

    The survival of Lactobacillus curvatus LTH 1174 (bac+) and (bac-) in combination with Escherichia coli LTH 1600 or Listeria innocua DSM20649 during transit through a dynamic model of the human stomach and small intestine (GIT model) was studied. Furthermore, we determined the digestion of curvacin A

  6. Escherichia coli F4 fimbriae specific lama single-domain antibody fragments effectively inhibit bacterial adhesion in vitro but poorly protect against diarrhea

    NARCIS (Netherlands)

    Harmsen, M.M.; Solt, van C.B.; Hoogendoorn, A.; Zijderveld, van F.G.; Niewold, T.A.; Meulen, van der J.

    2005-01-01

    Oral administration of polyclonal antibodies directed against enterotoxigenic Escherichia coli (ETEC) F4 fimbriae is used to protect against piglet post-weaning diarrhoea. For cost reasons, we aim to replace these polyclonal antibodies by recombinant llama single-domain antibody fragments (VHHs)

  7. Protective effects of lactoferrin chimera and bovine lactoferrin in a mouse model of enterohaemorrhagic Escherichia coli O157:H7 infection

    NARCIS (Netherlands)

    Flores-Villaseñor, H.; Canizalez-Román, A.; Velazquez-Roman, J.; Nazmi, K.; Bolscher, J.G.M.; Leon-Sicairos, N.

    2012-01-01

    Mice orally infected with enterohaemorrhagic Escherichia coli (EHEC) O157:H7 were used to evaluate the activity of bovine lactoferrin (bLF) and the synthetic peptide LFchimera. Groups of BALB/c mice inoculated intragastrically with EHEC O157:H7 showed chronic intestinal infection with the pathogen

  8. Site-directed mutagenesis of Arg58 and Asp86 of elongation factor Tu from Escherichia coli: effects on the GTPase reaction and aminoacyl-tRNA binding

    DEFF Research Database (Denmark)

    Knudsen, Charlotte Rohde; Clark, Brian F. C.

    1996-01-01

    Elongation factor Tu from Escherichia coli was mutated separately at positions Asp86 and Arg58, in order to shed light both on the GTPase mechanism of elongation factor Tu and on the binding of aminoacyl-tRNA. In addition, the binding of guanine nucleotides was investigated by determination...

  9. Effect of volumetric water content and clover (Trifolium incarnatum) on the survival of Escherichia coli O157:H7 in a soil matrix

    Science.gov (United States)

    Due to the inevitable introduction of zoonotic manure-born human pathogens, such as Escherichia coli O157:H7, into minimally processed, ready-to-eat and organic vegetable production systems via animal manure-based organic fertilizer, studies aimed at understanding the survival dynamics of these path...

  10. Effectiveness of different antimicrobial washes combined with freezing against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes inoculated on blueberries

    Science.gov (United States)

    To ensure the microbial safety of produce including blueberries, sanitization is a critical step. This study evaluated the efficacy of sanitizers when coupled with frozen storage, in inactivating Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes inoculated on wild blueberri...

  11. Enzyme organization in the proline biosynthetic pathway of Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Gamper, H; Moses, V

    1974-01-01

    The conversion of glutamic acid to proline by an Escherichia coli extract was studied. The activity was dependent upon the presence of ATP and NADPH and was largely unaffected by the presence of NH/sub 3/ or imidazole. The first two pathway enzymes appear to exist as a complex which stabilizes a labile intermediate postulated as ..gamma..-glutamyl phosphate. Attempted synthesis of this compound was unsuccessful due to its spontaneous cyclization to 2-pyrrolidone 5-carboxylate. Dissociation of the enzyme complex upon dilution of the extract is presumed responsible for an experimentally observed dilution effect. E. coli pro/sub A//sup -/ and pro/sub B//sup -/ auxotroph extracts failed to complement one another in the biosynthesis of proline. This is attributed to the lack of a dynamic equilibrium between the complex and its constituent enzymes. In vivo studies with E. coli showed no evidence for metabolic channeling in the final reaction of proline synthesis, the reduction of ..delta../sup 1/-pyrroline 5-carboxylate.

  12. Effects of Plant-Derived Extracts, Other Antimicrobials, and Their Combinations against Escherichia coli O157:H7 in Beef Systems.

    Science.gov (United States)

    Ko, Kyung Yuk; Geornaras, Ifigenia; Paik, Hyun-Dong; Kim, Kee-Tae; Sofos, John N

    2015-06-01

    The antimicrobial effects of thyme oil (TO), grapefruit seed extract (GSE), and basil essential oil, alone or in combination with cetylpyridinium chloride (CPC), sodium diacetate, or lactic acid, were evaluated against Escherichia coli O157:H7 in a moisture-enhanced beef model system. The model system was composed of a nonsterile beef homogenate to which NaCl (0.5%) and sodium tripolyphosphate (0.25%) were added, together with the tested antimicrobial ingredients. Beef homogenate treatments were inoculated (ca. 3 log CFU/ml) with rifampin-resistant E. coli O157:H7 (eight-strain mixture) and incubated at 15 °C (48 h). The most effective individual treatments were TO (0.25 or 0.5%) and GSE (0.5 or 1.0%), which immediately reduced (P extracts with CPC (0.02 or 0.04%) and sodium diacetate (0.25%) had an additive effect with respect to antibacterial activity. In a second study, antimicrobial interventions were evaluated for their efficacy in reducing surface contamination of E. coli O157:H7 on beef cuts and to determine the effect of these surface treatments on subsequent internalization of the pathogen during blade tenderization. Beef cuts (10 by 8 by 3.5 cm) were inoculated (ca. 4 log CFU/g) on one side with the rifampin-resistant E. coli O157:H7 strain mixture and were then spray treated (20 lb/in(2), 10 s) with water, GSE (5 and 10%), lactic acid (5%), or CPC (5%). Untreated (control) and spray-treated surfaces were then subjected to double-pass blade tenderization. Surface contamination (4.4 log CFU/g) of E. coli O157:H7 was reduced (P < 0.05) to 3.4 (5% CPC) to 4.1 (water or 5% GSE) log CFU/g following spray treatment. The highest and lowest transfer rates of pathogen cells from the surface to deeper tissues of blade-tenderized sections were obtained in the untreated control and CPC-treated samples, respectively.

  13. Effect of various conditions on inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in fresh-cut lettuce using ultraviolet radiation.

    Science.gov (United States)

    Kim, Yoon-Hee; Jeong, Seul-Gi; Back, Kyeong-Hwan; Park, Ki-Hwan; Chung, Myung-Sub; Kang, Dong-Hyun

    2013-09-16

    The effect of various conditions on inactivation of foodborne pathogens and quality of fresh-cut lettuce during ultraviolet (254 nm, UVC) radiation was investigated. Lettuce was inoculated with a cocktail of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and treated at different temperatures (4 and 25 °C), distances between sample and lamp (10 and 50 cm), type of exposure (illuminated from one or two sides), UV intensities (1.36 to 6.80 mW/cm²), and exposure times (0.5 to 10 min), sequentially. UV treatment at 25 °C for 1 min achieved 1.45-, 1.35-, and 2.12-log reductions in surface-inoculated E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, whereas the reduction of these pathogens at 4 °C was 0.31, 0.57, and 1.16 log, respectively. UV radiation was most effective when distance from UV lamp to the sample was minimal (10 cm) and radiation area was maximal (two-sided exposure). All UV intensities significantly (P0.05) different from those of nontreated samples up to 5 min exposure. However, these qualities significantly (Pradiation under optimized conditions could reduce foodborne pathogens without adversely affecting color quality properties of fresh-cut lettuce. © 2013 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  15. The Escherichia coli transcriptome linked to growth fitness

    Directory of Open Access Journals (Sweden)

    Bei-Wen Ying

    2016-03-01

    Full Text Available A series of Escherichia coli strains with varied genomic sequences were subjected to high-density microarray analyses to elucidate the fitness-correlated transcriptomes. Fitness, which is commonly evaluated by the growth rate during the exponential phase, is not only determined by the genome but is also linked to growth conditions, e.g., temperature. We previously reported genetic and environmental contributions to E. coli transcriptomes and evolutionary transcriptome changes in thermal adaptation. Here, we describe experimental details on how to prepare microarray samples that truly represent the growth fitness of the E. coli cells. A step-by-step record of sample preparation procedures that correspond to growing cells and transcriptome data sets that are deposited at the GEO database (GSE33212, GSE52770, GSE61739 are also provided for reference. Keywords: Transcriptome, Growth fitness, Escherichia coli, Microarray

  16. Production of caffeoylmalic acid from glucose in engineered Escherichia coli.

    Science.gov (United States)

    Li, Tianzhen; Zhou, Wei; Bi, Huiping; Zhuang, Yibin; Zhang, Tongcun; Liu, Tao

    2018-07-01

    To achieve biosynthesis of caffeoylmalic acid from glucose in engineered Escherichia coli. We constructed the biosynthetic pathway of caffeoylmalic acid in E. coli by co-expression of heterologous genes RgTAL, HpaBC, At4CL2 and HCT2. To enhance the production of caffeoylmalic acid, we optimized the tyrosine metabolic pathway of E. coli to increase the supply of the substrate caffeic acid. Consequently, an E. coli-E. coli co-culture system was used for the efficient production of caffeoylmalic acid. The final titer of caffeoylmalic acid reached 570.1 mg/L. Microbial production of caffeoylmalic acid using glucose has application potential. In addition, microbial co-culture is an efficient tool for producing caffeic acid esters.

  17. Effect of single or combined chemical and natural antimicrobial interventions on Escherichia coli O157:H7, total microbiota and color of packaged spinach and lettuce.

    Science.gov (United States)

    Poimenidou, Sofia V; Bikouli, Vasiliki C; Gardeli, Chryssavgi; Mitsi, Christina; Tarantilis, Petros A; Nychas, George-John; Skandamis, Panagiotis N

    2016-03-02

    Aqueous extract of Origanum vulgare (oregano), sodium hypochlorite (60 and 300 ppm of free chlorine), Citrox® (containing citric acid and phenolic compounds [bioflavonoids] as active ingredients), vinegar, lactic acid, and double combinations of Citrox, lactic acid and oregano were evaluated against Escherichia coli O157:H7 and total mesophilic microbiota on fresh-cut spinach and lettuce and for their impact on color of treated vegetables. Spinach and lettuce leaves were inoculated with E. coli O157:H7 to a level of 5-6 log CFU/g and immersed in washing solutions for 2 or 5 min at 20 °C, followed by rinsing with ice water (30s). Bacterial populations on vegetables were enumerated immediately after washing and after storage of the samples at 5 °C for 7 days under 20% CO2: 80% N2. No significant post-washing microbial reductions were achieved by chlorinated water, whereas after storage total microbiota was increased by 2.4 log CFU/g on lettuce. Vinegar wash was the most effective treatment causing E. coli O157:H7 reductions of 1.8-4.3 log CFU/g. During storage, pathogen was further decreased to below the detection limit level (lettuce during storage. Washing lettuce samples with oregano for 2 min resulted in 2.1 log CFU/g reduction of E. coli O157:H7. When Citrox was combined with oregano, 3.7-4.0 log CFU/g reduction was achieved on spinach and lettuce samples, with no significant effect on color parameters. Additionally, rinsing with ice water after decontamination treatments contributed to maintenance of color of the treated vegetables. In conclusion, the results indicated that vinegar, lactic acid or oregano aqueous extract alone or in combination, as alternative washing solutions to chlorine, may be effectively used to control E. coli O157:H7 and sustain acceptable appearance of fresh cut spinach and lettuce. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Inhibition of Coenzyme Qs Accumulation in Engineered Escherichia coli by High Concentration of Farnesyl Diphosphate

    OpenAIRE

    Samoudi, Mojtaba; Omid Yeganeh, Negar; Shahbani Zahiri, Hossein; Shariati, Parvin; Hajhosseini, Reza

    2015-01-01

    Background: Coenzyme Q 10 (CoQ 10 ) is an isoprenoid component used widely in nutraceutical industries. Farnesyl diphosphate synthase (FPPS) is a responsible enzyme for biosynthesis of farnesyl diphosphate (FPP), a key precursor for CoQs production. This research involved investigating the effect of FPPS over-expression on CoQs production in engineered CoQ 10 -producing Escherichia coli (E. coli). Methods: Two CoQ 10 -producing strains, as referred to E. coli Ba and E. coli Br, were transform...

  19. Draft Genome Sequence of Escherichia coli K-12 (ATCC 10798).

    Science.gov (United States)

    Dimitrova, Daniela; Engelbrecht, Kathleen C; Putonti, Catherine; Koenig, David W; Wolfe, Alan J

    2017-07-06

    Here, we present the draft genome sequence of Escherichia coli ATCC 10798. E. coli ATCC 10798 is a K-12 strain, one of the most well-studied model microorganisms. The size of the genome was 4,685,496 bp, with a G+C content of 50.70%. This assembly consists of 62 contigs and the F plasmid. Copyright © 2017 Dimitrova et al.

  20. Genes and proteins of Escherichia coli K-12.

    Science.gov (United States)

    Riley, M

    1998-01-01

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

  1. Predictors Of Non-Escherichia Coli Urinary Tract Infection.

    Science.gov (United States)

    Shaikh, Nader; Wald, Ellen R; Keren, Ron; Gotman, Nathan; Ivanova, Anastasia; Carpenter, Myra A; Moxey-Mims, Marva; Hoberman, Alejandro

    2016-11-01

    We aimed to determine which children are prone to non-Escherichia coli urinary tract infection (UTIs). We included 769 children with UTI. We found that circumcised males, Hispanic children, children without fever and children with grades 3 and 4 vesicoureteral reflux were more likely to have a UTI caused by organisms other than E. coli. This information may guide clinicians in their choice of antimicrobial therapy.

  2. Metabolic and Transcriptional Response to Cofactor Perturbations in Escherichia coli

    DEFF Research Database (Denmark)

    Holm, Anders Koefoed; Blank, L.M.; Oldiges, M.

    2010-01-01

    Metabolic cofactors such as NADH and ATP play important roles in a large number of cellular reactions, and it is of great interest to dissect the role of these cofactors in different aspects of metabolism. Toward this goal, we overexpressed NADH oxidase and the soluble F1-ATPase in Escherichia coli...... of redox and energy metabolism and should help in developing metabolic engineering strategies in E. coli....

  3. Intestinal Pathogenic Escherichia coli: Insights for Vaccine Development

    Directory of Open Access Journals (Sweden)

    Maricarmen Rojas-Lopez

    2018-03-01

    Full Text Available Diarrheal diseases are one of the major causes of mortality among children under five years old and intestinal pathogenic Escherichia coli (InPEC plays a role as one of the large causative groups of these infections worldwide. InPECs contribute significantly to the burden of intestinal diseases, which are a critical issue in low- and middle-income countries (Asia, Africa and Latin America. Intestinal pathotypes such as enteropathogenic E. coli (EPEC and enterotoxigenic E. coli (ETEC are mainly endemic in developing countries, while ETEC strains are the major cause of diarrhea in travelers to these countries. On the other hand, enterohemorrhagic E. coli (EHEC are the cause of large outbreaks around the world, mainly affecting developed countries and responsible for not only diarrheal disease but also severe clinical complications like hemorrhagic colitis and hemolytic uremic syndrome (HUS. Overall, the emergence of antibiotic resistant strains, the annual cost increase in the health care system, the high incidence of traveler diarrhea and the increased number of HUS episodes have raised the need for effective preventive treatments. Although the use of antibiotics is still important in treating such infections, non-antibiotic strategies are either a crucial option to limit the increase in antibiotic resistant strains or absolutely necessary for diseases such as those caused by EHEC infections, for which antibiotic therapies are not recommended. Among non-antibiotic therapies, vaccine development is a strategy of choice but, to date, there is no effective licensed vaccine against InPEC infections. For several years, there has been a sustained effort to identify efficacious vaccine candidates able to reduce the burden of diarrheal disease. The aim of this review is to summarize recent milestones and insights in vaccine development against InPECs.

  4. Effect of storage temperature on survival and recovery of thermal and extrusion injured Escherichia coli K-12 in whey protein concentrate and corn meal.

    Science.gov (United States)

    Ukuku, Dike O; Mukhopadhyay, Sudarsan; Onwulata, Charles

    2013-01-01

    Previously, we reported inactivation of Escherichia coli populations in corn product (CP) and whey protein product (WPP) extruded at different temperatures. However, information on the effect of storage temperatures on injured bacterial populations was not addressed. In this study, the effect of storage temperatures on the survival and recovery of thermal death time (TDT) disks and extrusion injured E. coli populations in CP and WPP was investigated. CP and WPP inoculated with E. coli bacteria at 7.8 log(10) CFU/g were conveyed separately into the extruder with a series 6300 digital type T-35 twin screw volumetric feeder set at a speed of 600 rpm and extruded at 35°C, 55°C, 75°C, and 95°C, or thermally treated with TDT disks submerged into water bath set at 35°C, 55°C, 75°C, and 95°C for 120 s. Populations of surviving bacteria including injured cells in all treated samples were determined immediately and every day for 5 days, and up to 10 days for untreated samples during storage at 5°C, 10°C, and 23°C. TDT disks treatment at 35°C and 55°C did not cause significant changes in the population of the surviving bacteria including injured populations. Extrusion treatment at 35°C and 55°C led to significant (pagar plates. The results of this study showed that further inactivation of the injured populations occurred during storage at 5°C for 5 days suggesting the need for immediate storage of 75°C extruded CP and WPP at 5°C for at least 24 h to enhance their microbial safety.

  5. Escherichia coli and Cronobacter sakazakii in 'Tommy Atkins' minimally processed mangos: Survival, growth and effect of UV-C and electrolyzed water.

    Science.gov (United States)

    Santo, David; Graça, Ana; Nunes, Carla; Quintas, Célia

    2018-04-01

    These studies were aimed at assessing the growing capacity of Escherichia coli and Cronobacter sakazakii and the effectiveness of Ultraviolet-C (UV-C) radiation, acidic electrolyzed (AEW) and neutral electrolyzed (NEW) waters in the inhibition of these bacteria on minimally processed 'Tommy Atkins' mangoes (MPM). The fruits were contaminated by dip inoculation and kept 10 days at 4, 8, 12 and 20 °C while enumerating bacteria. Contaminated mangoes were disinfected using UV-C (2.5, 5, 7.5 and 10 kJ/m 2 ), AEW, NEW and sodium hypochlorite (SH) and the microorganisms were monitored. None of the enterobacteria grew at 4, 8 and 12 °C regardless of having persisted during the 10-day period. At 20 °C, E. coli and C. sakazakii grew, after adaption phases of 48 h and 24 h, to values of 8.7 and 8.5 log cfu/g at day eight, respectively. E. coli showed the highest reduction counts on the MPM washed with NEW and SH (2.2 log cfu/g). UV-C was more effective in reducing C. sakazakii (2.4-2.6 log cfu/g), when compared to AEW, NEW and SH (1.2-1.8 log cfu/g). The efficacy of decontamination technologies depends on microorganisms, highlighting the importance of preventing contamination at the primary production and of combining different methods to increase the safety of fresh-cut fruits. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Microbial electrolytic disinfection process for highly efficient Escherichia coli inactivation

    DEFF Research Database (Denmark)

    Zhou, Shaofeng; Huang, Shaobin; Li, Xiaohu

    2018-01-01

    extensively studied for recalcitrant organics removal, its application potential towards water disinfection (e.g., inactivation of pathogens) is still unknown. This study investigated the inactivation of Escherichia coli in a microbial electrolysis cell based bio-electro-Fenton system (renamed as microbial......Water quality deterioration caused by a wide variety of recalcitrant organics and pathogenic microorganisms has become a serious concern worldwide. Bio-electro-Fenton systems have been considered as cost-effective and highly efficient water treatment platform technology. While it has been......]OH was identified as one potential mechanism for disinfection. This study successfully demonstrated the feasibility of bio-electro-Fenton process for pathogens inactivation, which offers insight for the future development of sustainable, efficient, and cost-effective biological water treatment technology....

  7. Escherichia Coli Removal from Water Using Electrophotocatalytic ...

    African Journals Online (AJOL)

    Michael Horsfall

    inactivation of bacterial microorganisms in areas with low ... disinfection of water contaminated with fecal indicators such as E. coli ... media, brain heart infusion, sodium chloride, sodium hydroxide ... furnace at temperature 105 and 320°C f0r 60 min. For 2- and .... charge of E. coli logarithmic growth phase might affect the ...

  8. Biochemical and serological characterization of Escherichia coli ...

    African Journals Online (AJOL)

    This study was designed to determine the isolation rate, serotypes and biochemical profiles of E. coli from colibacillosis and dead-in-shell embryos in Zaria, Northern-Nigeria. The isolation rate of E. coli from hatcheries studied were 4.67% and 7.50% from farms of Simtu Agricultural Company and National Animal Production ...

  9. Effectiveness of chlorine, organic acids and UV treatments in reducing Escherichia coli O157:H7 and Yersinia enterocolitica on apples.

    Science.gov (United States)

    Escudero, M E; Velázquez, L; Favier, G; de Guzmán, A M

    2003-06-01

    This study assessed the effectiveness of 200 and 500 ppm of chlorine and organic acids (0.5% lactic acid and 0.5% citric acid) in wash solutions, and UV radiation for reducing Escherichia coli O157:H7 and Yersinia enterocolitica on apples contaminated by two different methods. Residual levels of these pathogens after different treatments were compared. On dip inoculated apples, Y. enterocolitica reductions of 2.66 and 2.77 logs were obtained with 200 and 500 ppm chlorine combined with 0.5% lactic acid, respectively. The E. coli O157:H7 population decreased 3.35 log with 0.5% lactic acid wash solution, and 2.72 and 2.62 logs after 500 ppm chlorine and 500 ppm chlorine plus 0.5% lactic acid treatments, respectively. Similar reductions were obtained with UV radiation. On spot inoculated apples, significant (p acid treatment as compared with the control. In sectioned apples, microorganisms infiltrated in inner core region and pulp were not significantly (p apples. Reductions such as those obtained with 500 ppm chlorine plus 0.5% lactic acid solution were very proximal to the 5-log score required by FDA for apple disinfection.

  10. Antibiotic resistance of Verotoxigenic Escherichia coli isolated from vegetables

    Directory of Open Access Journals (Sweden)

    mojtaba boniadian

    2017-01-01

    Full Text Available Introduction: Human gastrointestinal disease caused by verotoxigenic Escherichia coli has been diagnosed for recent decades. Escherichia coli O157:H7 is the most important serotype of verotoxigenic Escherichia coli that cause hemolytic uremic syndrome and hemorrhagic colitis in humans. This study was conducted to determine the occurrence of verotoxigenic E. coli and antibiotic resistance of the isolates from vegetables. Materials and methods: A total of 500 fresh vegetable samples were collected randomly from retail shops in Shahrekord, Iran. E. coli was isolated and identified using bacteriological and biochemical tests. PCR method was used to identify the rbfE, stx1, stx2 and eae genes. Also, antibiotic resistance of the isolates was determined by disk diffusion method. Results: The results represented that among 25 isolates possess virulence genes, 40, 12 and 4% of the isolates contained eaeA, STx2, and both genes, respectively. But none of them contained H7, STx1, and rfbE genes. The antibiotic resistance pattern demonstrated that the isolates were highly resistant to Gentamycin and cefotoxime. Discussion and conclusion: The results of this study showed that the presence of verotoxigenic E.coli in vegetables; and high resistance of the isolates to antibiotics could be hazardous for public health.

  11. Inactivation and Gene Expression of a Virulent WastewaterEscherichia coliStrain and the Nonvirulent CommensalEscherichia coliDSM1103 Strain upon Solar Irradiation

    KAUST Repository

    Aljassim, Nada I.; Mantilla-Calderon, David; Wang, Tiannyu; Hong, Pei-Ying

    2017-01-01

    This study examined the decay kinetics and molecular responses of two Escherichia coli strains upon solar irradiation. The first is E. coli PI-7, a virulent and antibiotic-resistant strain that was isolated from wastewater and carries the emerging NDM-1 antibiotic resistance gene. The other strain, E. coli DSM1103, displayed lower virulence and antibiotic resistance than E. coli PI-7. In a buffer solution, E. coli PI-7 displayed a longer lag phase prior to decay and a longer half-life compared with E. coli DSM1103 (6.64 ± 0.63 h and 2.85 ± 0.46 min vs 1.33 ± 0.52 h and 2.04 ± 0.36 min). In wastewater, both E. coli strains decayed slower than they did in buffer. Although solar irradiation remained effective in reducing the numbers of both strains by more than 5-log10 in <24 h, comparative genomics and transcriptomics revealed differences in the genomes and overall regulation of genes between the two E. coli strains. A wider arsenal of genes related to oxidative stress, cellular repair and protective mechanisms were upregulated in E. coli PI-7. Subpopulations of E. coli PI-7 expressed genes related to dormancy and persister cell formation during the late decay phase, which may have accounted for its prolonged persistence. Upon prolonged solar irradiation, both E. coli strains displayed upregulation of genes related to horizontal gene transfer and antibiotic resistance. Virulence functions unique to E. coli PI-7 were also upregulated. Our findings collectively indicated that, whereas solar irradiation is able to reduce total cell numbers, viable E. coli remained and expressed genes that enable survival despite solar treatment. There remains a need for heightened levels of concern regarding risks arising from the dissemination of E. coli that may remain viable in wastewater after solar irradiation.

  12. Inactivation and Gene Expression of a Virulent WastewaterEscherichia coliStrain and the Nonvirulent CommensalEscherichia coliDSM1103 Strain upon Solar Irradiation

    KAUST Repository

    Aljassim, Nada I.

    2017-03-06

    This study examined the decay kinetics and molecular responses of two Escherichia coli strains upon solar irradiation. The first is E. coli PI-7, a virulent and antibiotic-resistant strain that was isolated from wastewater and carries the emerging NDM-1 antibiotic resistance gene. The other strain, E. coli DSM1103, displayed lower virulence and antibiotic resistance than E. coli PI-7. In a buffer solution, E. coli PI-7 displayed a longer lag phase prior to decay and a longer half-life compared with E. coli DSM1103 (6.64 ± 0.63 h and 2.85 ± 0.46 min vs 1.33 ± 0.52 h and 2.04 ± 0.36 min). In wastewater, both E. coli strains decayed slower than they did in buffer. Although solar irradiation remained effective in reducing the numbers of both strains by more than 5-log10 in <24 h, comparative genomics and transcriptomics revealed differences in the genomes and overall regulation of genes between the two E. coli strains. A wider arsenal of genes related to oxidative stress, cellular repair and protective mechanisms were upregulated in E. coli PI-7. Subpopulations of E. coli PI-7 expressed genes related to dormancy and persister cell formation during the late decay phase, which may have accounted for its prolonged persistence. Upon prolonged solar irradiation, both E. coli strains displayed upregulation of genes related to horizontal gene transfer and antibiotic resistance. Virulence functions unique to E. coli PI-7 were also upregulated. Our findings collectively indicated that, whereas solar irradiation is able to reduce total cell numbers, viable E. coli remained and expressed genes that enable survival despite solar treatment. There remains a need for heightened levels of concern regarding risks arising from the dissemination of E. coli that may remain viable in wastewater after solar irradiation.

  13. Immunomodulatory effect of non-viable components of probiotic culture stimulated with heat-inactivated Escherichia coli and Bacillus cereus on holoxenic mice.

    Science.gov (United States)

    Ditu, L M; Chifiriuc, M C; Bezirtzoglou, E; Marutescu, L; Bleotu, C; Pelinescu, D; Mihaescu, G; Lazar, V

    2014-01-01

    Competition of probiotic bacteria with other species from the intestinal microbiota involves different mechanisms that occur regardless of probiotics' viability. The objective of this paper was to assess the cytokine serum levels in holoxenic mice after oral administration of non-viable components (NVC) of Enterococcus faecium probiotic culture stimulated with heat-inactivated Escherichia coli and Bacillus cereus in comparison to NVC of unstimulated E. faecium probiotic culture. Probiotic E. faecium CMGb 16 culture, grown in the presence of heat-inactivated cultures of E. coli and B. cereus CMGB 102, was subsequently separated into supernatant (SN) and heat-inactivated cellular sediment (CS) fractions by centrifugation. Each NVC was orally administered to holoxenic mice (balb C mouse strain), in three doses, given at 24 hours. Blood samples were collected from the retinal artery, at 7, 14, and 21 days after the first administration of the NVC. The serum concentrations of IL-12 and tumor necrosis factor-alpha (TNF-α) interleukins were assessed by ELISA method. After the oral administration of SN component obtained from the probiotic culture stimulated with heat-inactivated cultures of B. cereus CMGB 102 and E. coli O28, the serum concentrations of IL-12 were maintained higher in the samples collected at 7 and 14 days post-administration. No specific TNF-α profile could be established, depending on stimulated or non-stimulated probiotic culture, NVC fraction, or harvesting time. The obtained results demonstrate that non-viable fractions of probiotic bacteria, stimulated by other bacterial species, could induce immunostimulatory effects mediated by cytokines and act, therefore, as immunological adjuvants.

  14. Effects of subinhibitory concentrations of antimicrobial agents on Escherichia coli O157:H7 Shiga toxin release and role of the SOS response.

    Science.gov (United States)

    Nassar, Farah J; Rahal, Elias A; Sabra, Ahmad; Matar, Ghassan M

    2013-09-01

    Treatment of Escherichia coli O157:H7 by certain antimicrobial agents often exacerbates the patient's condition by increasing either the release of preformed Shiga toxins (Stx) upon cell lysis or their production through the SOS response-triggered induction of Stx-producing prophages. Recommended subinhibitory concentrations (sub-MICs) of azithromycin (AZI), gentamicin (GEN), imipenem (IMI), and rifampicin (RIF) were evaluated in comparison to norfloxacin (NOR), an SOS-inducer, to assess the role of the SOS response in Stx release. Relative expression of recA (SOS-inducer), Q (late antitermination gene of Stx-producing prophage), stx1, and stx2 genes was assessed at two sub-MICs of the antimicrobials for two different strains of E. coli O157:H7 using reverse transcription-real-time polymerase chain reaction. Both strains at the two sub-MICs were also subjected to Western blotting for LexA protein expression and to reverse passive latex agglutination for Stx detection. For both strains at both sub-MICs, NOR and AZI caused SOS-induced Stx production (high recA, Q, and stx2 gene expression and high Stx2 production), so they should be avoided in E. coli O157:H7 treatment; however, sub-MICs of RIF and IMI induced Stx2 production in an SOS-independent manner except for one strain at the first twofold dilution below MIC of RIF where Stx2 production decreased. Moreover, GEN caused somewhat increased Stx2 production due to its mode of action rather than any effect on gene expression. The choice of antimicrobial therapy should rely on the antimicrobial mode of action, its concentration, and on the nature of the strain.

  15. Escherichia coli O26 IN RAW BUFFALO MILK: PRELIMINARY RESULTS

    Directory of Open Access Journals (Sweden)

    A. Rella

    2013-02-01

    Full Text Available Escherichia coli O26 is considered to be one of the most important food-borne pathogen. In this study, 120 buffalo milk samples collected in Lazio and in Apulia regions were tested for the presence of E. coli O26. One buffalo milk sample (0,8% tested positive for E. coli O26; the isolate was positive at the verocytotoxicity test and it showed resistance properties to different antimicrobial classes. These preliminary results highlight the need to monitor the foods of animal origin used for production and eaten by a wide range of persons, respect VTEC organism.

  16. Spontaneous Escherichia coli Meningitis Associated with Hemophagocytic Lymphohistiocytosis

    Directory of Open Access Journals (Sweden)

    Kuo-Hsuan Chang

    2006-01-01

    Full Text Available Spontaneous Escherichia coli meningitis has not been previously reported in association with hemophago-cytic lymphohistiocytosis (HLH. A previously healthy 72-year-old woman was admitted due to fever, nuchal rigidity, disturbed consciousness and splenomegaly. Anemia, thrombocytopenia and hyperfer-ritinemia developed on the 8th day of hospitalization. Cultures of cerebrospinal fluid and blood grew E. coli. Abundant macrophages overwhelmed erythrocytes in the bone marrow aspirate, confirming the presence of hemophagocytosis. E. coli meningitis was managed with a 40-day course of antibiotic treatment. However, the severity of anemia and thrombocytopenia progressed despite intensive transfusion therapy. The patient died of HLH on the 60th day of hospitalization.

  17. Sickness behavior in dairy cows during Escherichia coli mastitis

    DEFF Research Database (Denmark)

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

    2012-01-01

    The consequences of mastitis in terms of dairy cow behavior are relatively unknown. Future assessment of dairy cow welfare during mastitis will be facilitated by knowledge about the potential of mastitis to induce sickness behavior. Our aim was to examine behavior of dairy cows in the period from 2...... d before (d −2 and −1) to 3 d (d 0, 1, and 2) after experimental intramammary challenge with Escherichia coli. Effects of experimentally induced mastitis on behavior were examined in 20 primiparous Danish Holstein-Friesian cows, all 3 to 6 wk after calving and kept in tie stalls. After evening....... This knowledge can be useful for the development of welfare assessment protocols, early disease detection, and for future work aimed at understanding the behavioral needs of dairy cows suffering from mastitis....

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

    DEFF Research Database (Denmark)

    Agger, Morten; Scheutz, Flemming; Villumsen, Steen

    2015-01-01

    OBJECTIVES: A consensus has existed on not to treat verocytotoxin-producing Escherichia coli (VTEC)-infected individuals with antibiotics because of possible subsequent increased risk of developing haemolytic uraemic syndrome (HUS). The aim of this systematic review is to clarify the risk...... associated with antibiotic treatment during acute VTEC infection and in chronic VTEC carrier states. METHODS: A systematic search in PubMed identified 1 meta-analysis, 10 clinical studies and 22 in vitro/in vivo studies. RESULTS: Four clinical studies found an increased risk of HUS, four studies found...... no altered risk of HUS and two studies found a protective effect of antibiotics. In vitro and clinical studies suggest that DNA synthesis inhibitors should be avoided, whereas evidence from in vitro studies indicates that certain protein and cell wall synthesis inhibitors reduce the release of toxins from...

  19. Differential expression of the Escherichia coli autoaggregation factor antigen 43

    DEFF Research Database (Denmark)

    Schembri, Mark; Hjerrild, Louise; Gjermansen, Morten

    2003-01-01

    Antigen 43 (Ag43) is a self-recognizing surface adhesin found in most Escherichia coli strains. Due to its excellent cell-to-cell aggregation characteristics, Ag43 expression confers clumping and fluffing of cells and promotes biofilm formation. Ag43 expression is repressed by the cellular redox...

  20. Escherichia coli bacteraemia in patients with and without haematological malignancies

    DEFF Research Database (Denmark)

    Olesen, B; Kolmos, H J; Orskov, F

    1998-01-01

    We compared serotypes, virulence factors and susceptibility to antibiotics of Escherichia coli strains isolated from 282 patients with bacteraemia. Thirty-five of these were neutropenic patients with haematological malignancy and 247 were patients with a normal or raised total white blood cell co...

  1. DNA supercoiling depends on the phosphorylation potential in Escherichia coli

    DEFF Research Database (Denmark)

    Van Workum, M.; van Dooren, S.J.M; Oldenburg, N

    1996-01-01

    ATP/ADP ratios were varied in different ways and the degree of negative supercoiling was determined in Escherichia coli. Independent of whether the ATP/ADP ratio was reduced by a shift to anaerobic conditions, by addition of protonophore (dinitrophenol) or by potassium cyanide addition, DNA super...

  2. Properties of in situ Escherichia coli -D-glucuronidase (GUS ...

    African Journals Online (AJOL)

    A study of the activity of Escherichia coli -D-glucuronidase (GUS) in polluted stagnant and running water samples was performed with an objective of assessing the viability of a direct marker enzyme assay as a suitable alternative to membrane filtration for the indication of faecal pollution in water intended for drinking ...

  3. Multiple-Resistant Commensal Escherichia Coli from Nigerian ...

    African Journals Online (AJOL)

    Purpose: The antimicrobial susceptibility and virulence traits of 150 strains of Escherichia coli ... and ethical approval was obtained from the Health .... persist in the guts by virtue of the ability of such ... cases of diarrhoea in Ile-Ife and environs.

  4. Cytokine response to Escherichia coli in gnotobiotic pigs

    Czech Academy of Sciences Publication Activity Database

    Šplíchal, Igor; Šplíchalová, Alla; Trebichavský, Ilja

    2008-01-01

    Roč. 53, č. 2 (2008), s. 161-164 ISSN 0015-5632 R&D Projects: GA ČR GA523/05/0249 Institutional research plan: CEZ:AV0Z50200510 Keywords : germ-free pigs * escherichia coli * cytokine response Subject RIV: EE - Microbiology, Virology Impact factor: 1.172, year: 2008

  5. Binding of Divalent Magnesium by Escherichia coli Phosphoribosyl Diphosphate Synthetase

    DEFF Research Database (Denmark)

    Willemoës, Martin; Hove-Jensen, Bjarne

    1997-01-01

    The mechanism of binding of the substrates MgATP and ribose 5-phosphate as well as Mg2+ to the enzyme 5-phospho-d-ribosyl a-1-diphosphate synthetase from Escherichia coli has been analyzed. By use of the competive inhibitors of ATP and ribose 5-phosphate binding, a,ß-methylene ATP and (+)-1-a,2-a...

  6. Kwantitatief gevoeligheidsonderzoek met intra- en extramurale isolaten van Escherichia coli

    NARCIS (Netherlands)

    de Neeling AJ; de Jong J; Overbeek BP; de Bruin RW; Dessens-Kroon M; van Klingeren B

    1990-01-01

    Three Dutch laboratories for medical microbiology collected a total number of 1432 strains of Escherichia coli. Of these 995 were obtained from routine samples taken in clinic and policlinic, 290 had been sent spontaneously by general practitioners for microbiological examination and 147 had been

  7. in Escherichia coli with native cholesterol oxidase expressed

    African Journals Online (AJOL)

    The structure and bio-activity of an endogenous cholesterol oxidase from Brevibacterium sp. was compared to the same enzyme exogenously expressed in Escherichia coli BL21 (DE3) with and without N- or C-terminal his-tags. The different proteins were purified with affinity and subtractive protocols. The specific activity of ...

  8. Sequencing of Escherichia coli that cause persistent and transient Mastitis

    Science.gov (United States)

    The genomes of two strains of Escherichia coli that cause bovine mastitis were sequenced. These strains are known to be associated with persistent and transient mastitis: strain ECA-B causes a transient infection, and ECC-M leads to a persistent infection....

  9. Escherichia coli. A sanitary methodology for faecal water pollution tests

    International Nuclear Information System (INIS)

    Bonadonna, L.

    2001-01-01

    Among the traditional indictors of faecal water pollution, Escherichia coli has shown to fit better with the definition of indicator organism. Till now its recovery has been time-consuming and needs confirmation tests. In this report more rapid and direct methods, based on enzymatic reactions, are presented [it

  10. Antibiotic resistance profile of Escherichia coli isolated from five ...

    African Journals Online (AJOL)

    Information on the resistance profiles of clinical and non clinical human bacteria isolates in the developing countries can serve as important means of understanding the human pathogens drug resistance interactions in the zone. Escherichia coli isolated from five geopolitical zones of Nigeria were screened for anti-microbial ...

  11. Modeling base excision repair in Escherichia coli bacterial cells

    International Nuclear Information System (INIS)

    Belov, O.V.

    2011-01-01

    A model describing the key processes in Escherichia coli bacterial cells during base excision repair is developed. The mechanism is modeled of damaged base elimination involving formamidopyrimidine DNA glycosylase (the Fpg protein), which possesses several types of activities. The modeling of the transitions between DNA states is based on a stochastic approach to the chemical reaction description

  12. Occurrence of Escherichia coli in Brassica rapa L. chinensis ...

    African Journals Online (AJOL)

    Low quality water has become valuable resource with restricted or unrestricted use in food production depending on its quality. This study has quantified the occurrence of Escherichia coli in Brassica rapa L. chinensis (Chinese cabbage) vegetables and low quality irrigation water. A total of 106 samples including Chinese ...

  13. Physiological responses of Escherichia coli to far-ultraviolet radiation

    International Nuclear Information System (INIS)

    Swenson, P.A.

    1976-01-01

    The following topics are reviewed: photochemical damage to DNA; measurement of cell survival; DNA repair processes and genetics of radiation sensitivity; degradation of DNA and RNA; biochemical and physiological consequences; reactivation of bacteriophage in Escherichia coli cells; filament formation; influence of growth phase on survival after uv irradiation; and post-uv-irradiation treatment

  14. Production of jet fuel precursor monoterpenoids from engineered Escherichia coli

    DEFF Research Database (Denmark)

    Mendez-Perez, Daniel; Alonso-Gutierrez, Jorge; Hu, Qijun

    2017-01-01

    ). FPP biosynthesis diverts the carbon flux from monoterpene production to C15 products and quinone biosynthesis. In this study, we tested a chromosomal mutation of Escherichia coli's native FPP synthase (IspA) to improve GPP availability for the production of monoterpenes using a heterologous mevalonate...

  15. The incidence and antibiotics susceptibility of Escherichia coli O157 ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-02-22

    Feb 22, 2010 ... The incidence of Escherichia coli 0157: H7 was assessed in meat samples from slaughtered cattle in. Ibadan metropolis by culturing ... high quality farm to fork wholesome and safe meat for public consumption in Nigeria. Key words: EHEC .... Prevalence and in vitro antimicrobial susceptibility. Trop. Vet. 26.

  16. Prevalence of Escherichia coli virulence genes in patients with ...

    African Journals Online (AJOL)

    In this study, we investigated the prevalence of the virulence genes specific for five major pathogroups of diarrheagenic Escherichia coli (DEC) in primary cultures from diarrhoeagenic patients in Burkina Faso. Methodology: From September 2016 to Mars 2017, a total of 211 faecal samples from diarrhoeagenic patients from ...

  17. Comparative Genomics of Escherichia coli Strains Causing Urinary Tract Infections

    DEFF Research Database (Denmark)

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

    2011-01-01

    The virulence determinants of uropathogenic Escherichia coli have been studied extensively over the years, but relatively little is known about what differentiates isolates causing various types of urinary tract infections. In this study, we compared the genomic profiles of 45 strains from a range...

  18. Expression and purification of recombinant hemoglobin in Escherichia coli

    DEFF Research Database (Denmark)

    Natarajan, Chandrasekhar; Jiang, Xiaoben; Fago, Angela

    2011-01-01

    BACKGROUND: Recombinant DNA technologies have played a pivotal role in the elucidation of structure-function relationships in hemoglobin (Hb) and other globin proteins. Here we describe the development of a plasmid expression system to synthesize recombinant Hbs in Escherichia coli, and we describe...

  19. Search for Enterohaemorrhagic Escherichia coli O157:H7 and ...

    African Journals Online (AJOL)

    Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 and Salmonella enterica are important zoonotic bacteria responsible for enteric infections in humans. The present study investigated the possible role of kittens in the zoonotic transmission of antimicrobial resistant EHEC O157 and Salmonella enterica to human using ...

  20. Antibiotic Sensitivity Profile of Escherichia coli Isolated from Poultry ...

    African Journals Online (AJOL)

    A cross sectional study involving 300 cloaca swabs from apparently healthy birds from 8 small-medium scale poultry farms in Ibadan Oyo State was carried out. A total of 201 (67%) Escherichia coli isolates were recovered from the birds and they were subjected to in-vitro antibiotic sensitivity test by agar gel diffusion method.

  1. Increasing the permeability of Escherichia coli using MAC13243

    DEFF Research Database (Denmark)

    Muheim, Claudio; Götzke, Hansjörg; Eriksson, Anna U.

    2017-01-01

    molecules that make the outer membrane of Escherichia coli more permeable. We identified MAC13243, an inhibitor of the periplasmic chaperone LolA that traffics lipoproteins from the inner to the outer membrane. We observed that cells were (1) more permeable to the fluorescent probe 1-N...

  2. Molecular characterization of the Escherichia coli asymptomatic bacteriuria strain 83972

    DEFF Research Database (Denmark)

    Klemm, Per; Hancock, Viktoria; Ulett, G.C.

    2006-01-01

    Escherichia coli 83972 is a clinical asymptomatia bacteriuric isolate that is able to colonize the human urinary bladder without inducing an immune response. Here we demonstrate that one of the mechanisms by which this strain has become attenuated is through the mutation of its genes encoding type...

  3. Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation.

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2015-02-26

    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. Copyright © 2015 Doan et al.

  5. Protein export in bacillus subtilis and escherichia coli

    NARCIS (Netherlands)

    Dijl, Jan Maarten van

    1990-01-01

    The export of heterologous proteins in Bacillus subtilis and Escherichia coli is often inefficient. Frequently observed problems are: 1) accumulation of the precursor form of the exported protein in the cytoplasm or in the membrane; 2), inefficient or incorrect processing of the precursor; 3),

  6. Escherichia coli and virus isolated from ''sticky kits''

    DEFF Research Database (Denmark)

    Jørgensen, M.; Scheutz, F.; Strandbygaard, Bertel

    1996-01-01

    A total of 121 Escherichia coli strains isolated from 3-week-old mink kits were serotyped and examined for virulence factors. 56 strains were isolated from healthy kits while 65 were from ''sticky kits''. Among these, 34 different serotypes were detected. No difference in serotypes or the presenc...

  7. Hydrogenase-3 contributes to anaerobic acid resistance of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Ken Noguchi

    Full Text Available BACKGROUND: Hydrogen production by fermenting bacteria such as Escherichia coli offers a potential source of hydrogen biofuel. Because H(2 production involves consumption of 2H(+, hydrogenase expression is likely to involve pH response and regulation. Hydrogenase consumption of protons in E. coli has been implicated in acid resistance, the ability to survive exposure to acid levels (pH 2-2.5 that are three pH units lower than the pH limit of growth (pH 5-6. Enhanced survival in acid enables a larger infective inoculum to pass through the stomach and colonize the intestine. Most acid resistance mechanisms have been defined using aerobic cultures, but the use of anaerobic cultures will reveal novel acid resistance mechanisms. METHODS AND PRINCIPAL FINDINGS: We analyzed the pH regulation of bacterial hydrogenases in live cultures of E. coli K-12 W3110. During anaerobic growth in the range of pH 5 to 6.5, E. coli expresses three hydrogenase isoenzymes that reversibly oxidize H(2 to 2H(+. Anoxic conditions were used to determine which of the hydrogenase complexes contribute to acid resistance, measured as the survival of cultures grown at pH 5.5 without aeration and exposed for 2 hours at pH 2 or at pH 2.5. Survival of all strains in extreme acid was significantly lower in low oxygen than for aerated cultures. Deletion of hyc (Hyd-3 decreased anoxic acid survival 3-fold at pH 2.5, and 20-fold at pH 2, but had no effect on acid survival with aeration. Deletion of hyb (Hyd-2 did not significantly affect acid survival. The pH-dependence of H(2 production and consumption was tested using a H(2-specific Clark-type electrode. Hyd-3-dependent H(2 production was increased 70-fold from pH 6.5 to 5.5, whereas Hyd-2-dependent H(2 consumption was maximal at alkaline pH. H(2 production, was unaffected by a shift in external or internal pH. H(2 production was associated with hycE expression levels as a function of external pH. CONCLUSIONS: Anaerobic growing

  8. Hydrogenase-3 contributes to anaerobic acid resistance of Escherichia coli.

    Science.gov (United States)

    Noguchi, Ken; Riggins, Daniel P; Eldahan, Khalid C; Kitko, Ryan D; Slonczewski, Joan L

    2010-04-12

    Hydrogen production by fermenting bacteria such as Escherichia coli offers a potential source of hydrogen biofuel. Because H(2) production involves consumption of 2H(+), hydrogenase expression is likely to involve pH response and regulation. Hydrogenase consumption of protons in E. coli has been implicated in acid resistance, the ability to survive exposure to acid levels (pH 2-2.5) that are three pH units lower than the pH limit of growth (pH 5-6). Enhanced survival in acid enables a larger infective inoculum to pass through the stomach and colonize the intestine. Most acid resistance mechanisms have been defined using aerobic cultures, but the use of anaerobic cultures will reveal novel acid resistance mechanisms. We analyzed the pH regulation of bacterial hydrogenases in live cultures of E. coli K-12 W3110. During anaerobic growth in the range of pH 5 to 6.5, E. coli expresses three hydrogenase isoenzymes that reversibly oxidize H(2) to 2H(+). Anoxic conditions were used to determine which of the hydrogenase complexes contribute to acid resistance, measured as the survival of cultures grown at pH 5.5 without aeration and exposed for 2 hours at pH 2 or at pH 2.5. Survival of all strains in extreme acid was significantly lower in low oxygen than for aerated cultures. Deletion of hyc (Hyd-3) decreased anoxic acid survival 3-fold at pH 2.5, and 20-fold at pH 2, but had no effect on acid survival with aeration. Deletion of hyb (Hyd-2) did not significantly affect acid survival. The pH-dependence of H(2) production and consumption was tested using a H(2)-specific Clark-type electrode. Hyd-3-dependent H(2) production was increased 70-fold from pH 6.5 to 5.5, whereas Hyd-2-dependent H(2) consumption was maximal at alkaline pH. H(2) production, was unaffected by a shift in external or internal pH. H(2) production was associated with hycE expression levels as a function of external pH. Anaerobic growing cultures of E. coli generate H(2) via Hyd-3 at low external pH, and

  9. ESBL-Producing Escherichia coli

    DEFF Research Database (Denmark)

    Hertz, Frederik Boetius

    Urinary tract infection (UTI) is one the most common bacterial infections and is regularly treated in primary health care. The most common cause of UTI is extraintestinal pathogenic Escherichia coli (ExPEC) already present in the intestinal microflora, often as the dominating strain. Resistance...... in E.coli is increasing and especially isolates producing Extended-Spectrum Beta-Lactamases (ESBL) have been reported worldwide. Treatment of UTI is usually initiated by the general practitioners and a significant proportion of clinical isolates are now resistant to first line antibiotics. The global...... to investigate (i) antibiotics involved in selection of ESBL-producing E.coli, in an experimental mouse model in vivo, (ii) risk factors for UTI with ESBL-producing E.coli and (iii) to describe the phylogenetic composition of E.coli populations with different resistance patterns. We found that different...

  10. Elimination of Escherichia coli and Salmonella in Clam by Using Zeolite in a Station of Depuration.

    Science.gov (United States)

    Gdoura, Morsi; Sellami, Hanen; Khannous, Lamia; Ketata, Najib; Neila, Idriss Ben; Traore, Al Ibrahim; Chekir, Zouhair; Gdoura, Radhouane

    2017-09-01

      The application of natural zeolite for water and wastewater treatment has been carried out and is still a promising technique in environmental cleaning processes. Natural zeolite can be used to improve the purification process of clams (Ruditapes decussatus). Thus, our study aimed at improving the clam purification system in order to reduce Escherichia coli and eliminate Salmonella in samples artificially contaminated with this bacterium using a natural zeolite to replace the biological filter. The results showed that zeolite used in a depuration system improved the clam purification process. Moreover, natural zeolite exhibited high performance in the adsorption of bacteria and allowed to reduce the Escherichia coli abundance in 24 h, thus ensuring purified clams conformity with the ISO 16649-3 standard. These results indicate the beneficial effects of using zeolite in the adsorption of bacteria and the reduction in the abundance of Escherichia coli and set the Salmonella from marine organisms.

  11. Effect of milk fat content on the performance of ohmic heating for inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium and Listeria monocytogenes.

    Science.gov (United States)

    Kim, S-S; Kang, D-H

    2015-08-01

    The effect of milk fat content on ohmic heating compared to conventional heating for inactivation of food-borne pathogens was investigated. Sterile cream was mixed with sterile buffered peptone water and adjusted to 0, 3, 7, 10% (w/v) milk fat content. These samples with varying fat content were subjected to ohmic and conventional heating. The effect of milk fat on temperature increase and electrical conductivity were investigated. Also, the protective effect of milk fat on the inactivation of foodborne pathogens was studied. For conventional heating, temperatures of samples increased with time and were not significantly (P > 0.05) different regardless of fat content. Although the inactivation rate of Escherichia coli O157:H7, Salmonella Typhimurium and L. monocytogens decreased in samples of 10% fat content, a protective effect was not observed for conventional heating. In contrast with conventional heating, ohmic heating was significantly affected by milk fat content. Temperature increased more rapidly with lower fat content for ohmic heating due to higher electrical conductivity. Nonuniform heat generation of nonhomogeneous fat-containing samples was verified using a thermal infrared camera. Also, the protective effect of milk fat on E. coli O157:H7 and Listeria monocytogenes was observed in samples subjected to ohmic heating. These results indicate that food-borne pathogens can survive in nonhomogeneous fat-containing foods subjected to ohmic heating. Therefore, more attention is needed regarding ohmic heating than conventional heating for pasteurizing fat-containing foods. The importance of adequate pasteurization for high milk fat containing foods was identified. © 2015 The Society for Applied Microbiology.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    Escherichia coli is the most important etiological agent of urinary tract infections (UTIs). Unlike uropathogenic E. coli, which causes symptomatic infections, asymptomatic bacteriuria (ABU) E. coli strains typically lack essential virulence factors and colonize the bladder in the absence...

  13. Mutagenic DNA repair in Escherichia coli. VII

    International Nuclear Information System (INIS)

    Bridges, B.A.; Mottershead, R.P.

    1978-01-01

    Incubation of E. coli WP2 in the presence of chloramphenicol (CAP) for 90 min before and 60 min after γ-irradiation had no effect on the induction of Trp + mutations. Bacteria that had been treated with CAP for 90 min prior to UV irradiation showed normal or near normal yields of induced mutations to streptomycin or colicin E2 resistance. Most of these mutations lost their photoreversibility (indicating 'fixation') during continued incubation with CAP for a further 60 min after irradiation, during which time neither protein nor DNA synthesis was detectable. It is suggested that CAP-sensitive protein synthesis is not required for mutagenic (error-prone) repair of lesions in pre-existing DNA, arguing against an inducible component in this repair. In contrast the frequency of UV-induced mutations to Trp + (largely at suppressor loci) was drastically reduced by CAP pretreatment, confirming the need for an active replication fork for UV-mutagenesis at these loci. It is known from the work of others that CAP given after UV abolishes mutagenesis at these loci. It is concluded that CAP-sensitive protein synthesis (consistent with a requirement for an inducible function) is necessary for mutagenic repair only in newly-replicated DNA (presumably at daughter strand gaps) and not in pre-existing DNA. The data are consistent with but do not prove the hypothesis that CAP-sensitive and insensitive modes of mutagenesis reflect minor differences in the operation of a single basic mutagenic repair system. (Auth.)

  14. Voltage-gated calcium flux mediates Escherichia coli mechanosensation.

    Science.gov (United States)

    Bruni, Giancarlo N; Weekley, R Andrew; Dodd, Benjamin J T; Kralj, Joel M

    2017-08-29

    Electrically excitable cells harness voltage-coupled calcium influx to transmit intracellular signals, typically studied in neurons and cardiomyocytes. Despite intense study in higher organisms, investigations of voltage and calcium signaling in bacteria have lagged due to their small size and a lack of sensitive tools. Only recently were bacteria shown to modulate their membrane potential on the timescale of seconds, and little is known about the downstream effects from this modulation. In this paper, we report on the effects of electrophysiology in individual bacteria. A genetically encoded calcium sensor expressed in Escherichia coli revealed calcium transients in single cells. A fusion sensor that simultaneously reports voltage and calcium indicated that calcium influx is induced by voltage depolarizations, similar to metazoan action potentials. Cytoplasmic calcium levels and transients increased upon mechanical stimulation with a hydrogel, and single cells altered protein concentrations dependent on the mechanical environment. Blocking voltage and calcium flux altered mechanically induced changes in protein concentration, while inducing calcium flux reproduced these changes. Thus, voltage and calcium relay a bacterial sense of touch and alter cellular lifestyle. Although the calcium effectors remain unknown, these data open a host of new questions about E. coli , including the identity of the underlying molecular players, as well as other signals conveyed by voltage and calcium. These data also provide evidence that dynamic voltage and calcium exists as a signaling modality in the oldest domain of life, and therefore studying electrophysiology beyond canonical electrically excitable cells could yield exciting new findings.

  15. The effect of environmental factors and migration dynamics on the prevalence of antibiotic-resistant Escherichia coli in estuary environments

    OpenAIRE

    Na, Guangshui; Lu, Zihao; Gao, Hui; Zhang, Linxiao; Li, Qianwei; Li, Ruijing; Yang, Fan; Huo, Chuanlin; Yao, Ziwei

    2018-01-01

    Understanding the antibiotic resistance transmission mechanisms and migration dynamics of antibiotic-resistant bacteria (ARB) in the natural environment is critical given the increasing prevalence of antibiotic resistance. The aim of this study was to examine the fate of sulfonamide-resistant fecal bacteria (E. coli) in an estuary ecosystem and to explore the role and contribution of environmental factors in this process. The prevalence of sulfonamide-resistance status of E. coli was analyzed...

  16. Characterization of diarrhoeagenic Escherichia coli isolates in Jordanian children.

    Science.gov (United States)

    Shehabi, Asem A; Bulos, Najawa-Kuri; Hajjaj, Kamal G

    2003-01-01

    In a prospective study carried out among Jordanian children in Amman, a total of 73/250 (29.2%) stool specimens were positive for 1 or more diarrhoeagenic Escherichia coli strains using a multiplex polymerase chain reaction method. This study indicated that diarrhoeagenic E. coli isolates were found frequently more in stools of children with diarrhoea (34%) than without diarrhoea (23.1%), but without any significant difference (p > 0.05). The predominant diarrhoeagenic E. coli strains associated with diarrhoea were enteropathogenic E. coli (11.3%), followed by enterotoxigenic E. coli (9.8%) and enteroaggrative E. coli (9%), whereas in the control group these were 4.3%, 11.1% and 6%, respectively. Enteroinvasive E. coli strains (2.9%) were found only in stools of children with diarrhoea. This study revealed the absence of enterohaemorrhagic E. coli in both diarrhoeal and control stools, and found that diarrhoeagenic E. coli isolates were highly resistance to tetracycline (55%), co-trimoxazole (60%) and ampicillin (89%), which are commonly used antibiotics in Jordan.

  17. Evaluating Antimicrobial Effects of Centaurea Plant’s Essential Oil on Pathogenic Bacteria: Staphylococcus Aureus, Staphylococcus Epidermidis, and Escherichia Coli Isolated from Clinical Specimens

    Directory of Open Access Journals (Sweden)

    Haedeh Mobaiyen

    2016-03-01

    Full Text Available Background & Objectives :Nowadays, development of drug resistance against chemical antimicrobial drugs has attracted attention using medicinal plants in treatment of infections. The aim of this study is to evaluate the antimicrobial effects of two species of Centaurea plant’s essential oil on drug resistant clinical isolates of three pathogenic isolates. Materials & Methods :The studied plants were collected from Marand city in East Azerbaijan, Iran and were confirmed as Centaurea Depressa M.B. and Centaurea Cyanus L. by botanists of Iran Agriculture Organization. The essential oil of these plants (Stems and leaf were extracted via steam distillation method by Clevenger, and their antimicrobial effects were studied by well diffusion method in the abovementioned bacteria. The components of essential oil were identified by injection to gas chromatography linked to mass spectrometry (GC/M. Results :The results of this study prove that the essential oils from the abovementioned plants have bactericidal effects. The most antibacterial effect is observed in Escherichia coli strains. The results of GC/MS chromatography reveal that the essential oils of Centaurea Depressa M.B. and Centaurea Cyanus L. have 28 and 32 compounds, respectively. Conclusion: This study confirmed that the grasses could be used in medicinal plants group with antibacterial properties. However, their effects in vivo must be evaluated and the most effective component of them must be identified carefully so that they can be applied commonly as an alternative synthetic drug in treating infections.

  18. Meta-analysis of the Effects of Sanitizing Treatments on Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes Inactivation in Fresh Produce

    Science.gov (United States)

    Prado-Silva, Leonardo; Cadavez, Vasco; Gonzales-Barron, Ursula; Rezende, Ana Carolina B.

    2015-01-01

    The aim of this study was to perform a meta-analysis of the effects of sanitizing treatments of fresh produce on Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes. From 55 primary studies found to report on such effects, 40 were selected based on specific criteria, leading to more than 1,000 data on mean log reductions of these three bacterial pathogens impairing the safety of fresh produce. Data were partitioned to build three meta-analytical models that could allow the assessment of differences in mean log reductions among pathogens, fresh produce, and sanitizers. Moderating variables assessed in the meta-analytical models included type of fresh produce, type of sanitizer, concentration, and treatment time and temperature. Further, a proposal was done to classify the sanitizers according to bactericidal efficacy by means of a meta-analytical dendrogram. The results indicated that both time and temperature significantly affected the mean log reductions of the sanitizing treatment (P vegetables (for example, 3.04 mean log reductions [2.32 to 3.76] obtained for carrots). Among the pathogens, E. coli O157:H7 was more resistant to ozone (1.6 mean log reductions), while L. monocytogenes and Salmonella presented high resistance to organic acids, such as citric acid, acetic acid, and lactic acid (∼3.0 mean log reductions). With regard to the sanitizers, it has been found that slightly acidic electrolyzed water, acidified sodium chlorite, and the gaseous chlorine dioxide clustered together, indicating that they possessed the strongest bactericidal effect. The results reported seem to be an important achievement for advancing the global understanding of the effectiveness of sanitizers for microbial safety of fresh produce. PMID:26362982

  19. Effect of Pressure-Induced Changes in the Ionization Equilibria of Buffers on Inactivation of Escherichia coli and Staphylococcus aureus by High Hydrostatic Pressure

    Science.gov (United States)

    Gayán, Elisa; Condón, Santiago; Álvarez, Ignacio; Nabakabaya, Maria

    2013-01-01

    Survival rates of Escherichia coli and Staphylococcus aureus after high-pressure treatment in buffers that had large or small reaction volumes (ΔV°), and which therefore underwent large or small changes in pH under pressure, were compared. At a low buffer concentration of 0.005 M, survival was, as expected, better in MOPS (morpholinepropanesulfonic acid), HEPES, and Tris, whose ΔV° values are approximately 5.0 to 7.0 cm3 mol−1, than in phosphate or dimethyl glutarate (DMG), whose ΔV° values are about −25 cm3 mol−1. However, at a concentration of 0.1 M, survival was unexpectedly better in phosphate and DMG than in MOPS, HEPES, or Tris. This was because the baroprotective effect of phosphate and DMG increased much more rapidly with increasing concentration than it did with MOPS, HEPES, or Tris. Further comparisons of survival in solutions of salts expected to cause large electrostriction effects (Na2SO4 and CaCl2) and those causing lower electrostriction (NaCl and KCl) were made. The salts with divalent ions were protective at much lower concentrations than salts with monovalent ions. Buffers and salts both protected against transient membrane disruption in E. coli, but the molar concentrations necessary for membrane protection were much lower for phosphate and Na2SO4 than for HEPES and NaCl. Possible protective mechanisms discussed include effects of electrolytes on water compressibility and kosmotropic and specific ion effects. The results of this systematic study will be of considerable practical significance in studies of pressure inactivation of microbes under defined conditions but also raise important fundamental questions regarding the mechanisms of baroprotection by ionic solutes. PMID:23624471

  20. Resistance Escherichia coli isolates to antibiotics from the organ samples originating from swine farms

    OpenAIRE

    Došen R.; Prodanov-Radulović J.; Pušić I.; Stojanov I.; Stojanović D.; Ratajac R.

    2011-01-01

    Bacteria Escherichia coli (E.coli) is a ubiquitous microorganism with a different serotypes, that cause septicemia in neonatal piglets, diarrhea in suckling piglets, diarrhea and edemic disease in weaned piglets. Vaccination and antibiotic treatment are less effective ways in solving the problem, especially when the category of pig is not taken into consideration, as well as feed safety and chemical composition of feed. The resistance of pathogens depends o...

  1. [Virulence markers of Escherichia coli O1 strains].

    Science.gov (United States)

    Makarova, M A; Kaftyreva, L A; Grigor'eva, N S; Kicha, E V; Lipatova, L A

    2011-01-01

    To detect virulence genes in clinical isolates of Escherichia coli O1 using polymerase chain reaction (PCR). One hundred and twenty strains of E.coli O1 strains isolated from faeces of patients with acute diarrhea (n = 45) and healthy persons (n = 75) were studied. PCR with primers for rfb and fliC genes, which control synthesis of O- and H- antigens respectively, was used. Fourteen virulence genes (pap, aaf, sfa, afa, eaeA, bfpA, ial, hly, cnf, stx1, stx2, lt, st, and aer) were detected by PCR primers. K1-antigen was determined by Pastorex Meningo B/E. coli O1 kit (Bio-Rad). rfb gene controlling O-antigen synthesis in serogroup O1 as well as fliC gene controlling synthesis of H7 and K1 antigens were detected in all strains. Thus all E. coli strains had antigenic structure O1:K1 :H-:F7. Virulence genes aafl, sfa, afa, eaeA, bfpA, ial, hly, cnf, stx1, stx2, lt, and st were not detected. All strains owned pap and aer genes regardless of the presence of acute diarrhea symptoms. It was shown that E. coli O1:KI:H-:F7 strains do not have virulence genes which are characteristic for diarrhea-causing Escherichia. In accordance with the presence of pap and aer genes they could be attributed to uropathogenic Escherichia (UPEC) or avian-pathogenic Escherichia (APEC). It is necessary to detect virulence factors in order to determine E. coli as a cause of intestinal infection.

  2. Optimizing strategy for Escherichia coli growth and hydrogen production during glycerol fermentation in batch culture: Effects of some heavy metal ions and their mixtures

    International Nuclear Information System (INIS)

    Trchounian, Karen; Poladyan, Anna; Trchounian, Armen

    2016-01-01

    Highlights: • Effects of heavy metals on Escherichia coli were revealed during glycerol fermentation at pH 6.5. • Ni"2"+ + Fe"2"+ (0.05 mM) mixture stimulated up to 1.5-fold bacterial biomass yield. • Ni"2"+ + Fe"3"+ (0.05 mM), Ni"2"+ + Fe"3"+ + Mo"6"+ (0.02 mM) and Fe"3"+ + Mo"6"+ enhanced (up to 3-fold) H_2 production. • Discrimination between Fe"2"+ and Fe"3"+ was important for H_2 production. • Cu"+ and Cu"2"+ (0.1 mM) inhibited H_2 production. - Abstract: Hydrogen (H_2) is well-known effective, ecologically clean and renewable fuel. Bacterial H_2 production is a promising one and its use in industrial level is expected to increase in the nearest future to establish sustainable and renewable energy source. Escherichia coli wild type BW25113 growth yield was shown to be stimulated 1.3–1.5-fold by nickel (Ni"2"+), iron (Fe"2"+, Fe"3"+) ions and by some metal ion mixtures: Ni"2"+ + Fe"2"+ + molybdenum (Mo"6"+), Ni"2"+ + Fe"3"+, Ni"2"+ + Fe"2"+ and Mo"6"+ + Fe"3"+ in low concentrations (<0.05 mM) stimulated the growth during glycerol (10 g L"−"1) fermentation up to stationary phase at pH 6.5; Ni"2"+ + Fe"2"+ mixture showed the maximal effect. However, the same concentrations of these metals and their mixtures had no effects or slightly inhibited bacterial specific growth rate: it was suppressed ∼1.2-fold upon Ni"2"+, Fe"3"+, Mo"6"+ and Ni"2"+ + Mo"6"+ mixture supplementation. H_2 production by E. coli from glycerol was observed with the yield of 0.75 ± 0.02 mmol L"−"1. Moreover, H_2 yield was markedly stimulated 1.7–3-fold in the presence of Ni"2"+ + Fe"3"+, Ni"2"+ + Fe"3"+ + Mo"6"+ and Fe"3"+ + Mo"6"+ mixtures, but not sole metals: maximal stimulation was established by Fe"3"+ + Mo"6"+ mixture with the concentrations of 0.05 mM and 0.02 mM, respectively. While copper (Cu"+, Cu"2"+) ions in low concentration (0.1 mM) had H_2 production suppressing effect. The results point out that some heavy metal ions and their mixtures can stimulate E

  3. EFEK SUPLEMENTASI LAKTOFERIN PADA SUSU FORMULA TERHADAP AVAILABILITAS ZAT BESI, OKSIDASI LEMAK DAN PERTUMBUHAN Escherichia coli PADA SALURAN PENCERNAAN TIKUS [The Effects of Lactoferrin Supplementation to Infant Formula on Iron Availability, Lipid Oxidation and Escherichia coli Growth in RatsIntestine

    Directory of Open Access Journals (Sweden)

    Enny Purwati Nurlaili 1

    2002-12-01

    Full Text Available A research on lactoferrin supplementation to infant formula has been conducted. The objectives of this research were to study the effects of consumption of the supplemented formula on iron availability, lipid oxidation and growth of Escherichia coli in the intestine. Fifthly newly born rats and their mother (10 rats were used.They were divided into 5 groups of 10 newly born and 2 mother rats, and were given five different infant formula respectivelly i.e. FEAN (inorganic Fe supplementation, FEOR ( lactoferrin supplementation, FECAMP (inorganic and lactoferrin supplementation, Control (no Fe supplementation and Placebo. FeSO4. 7 H2O and lactoferrin were used as the source of inorganic and organic Fe respectively. During the experiment the rat baby also got regular milk from their mothers which were fed by AIN 93 diet. After 30 days of intervention, blood were withdrawn from the retro orbital plexus for Hb, Fe and TBARS determination. The rats were executed and liver was taken for Fe and TBARS analysis and large intestine were withdrawn for Escherichia coli determination. It was found that Fe supplementation of the formula have no effects on the serum total Fe, increase the total hemoglobin of the baby but was not significantly different between the sources of the Fe. Total Fe of the liver was highest in FECAMP and FEOR rats (101.3 ppm and 83.38 ppm, respectively and lowest in the Placebo groups (58.1 ppm. Inorganic Fe supplementation increase TBARS of the serum and liver of the rats. Number of total Escherichia coli was lowest in FEOR groups (1.7 10 7 cfu and was highest in FEAN rats (7.5 10 7 cfu.

  4. Early effects of Escherichia coli endotoxin infusion on vasopressin-stimulated breakdown and metabolism of inositol lipids in rat hepatocytes

    International Nuclear Information System (INIS)

    Rodriguez de Turco, E.B.; Spitzer, J.A.

    1988-01-01

    The turnover of vasopressin-stimulated 32P-phosphoinositides and 32P-phosphatidic acid and accumulation of [2-3H]-inositol phosphates were examined in hepatocytes from rats infused i.v. with saline and E. coli endotoxin for 3 hrs. Within 60s of VP stimulation the decrease in phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate labeling as well as the increased uptake of 32P into phosphatidic acid were similar in both groups. However, at a later time (300s) the 32P-phosphatidylinositol turnover was greatly decreased concomitantly with a higher labeling of phosphatidic acid. The accumulation of [2-3H]-inositol phosphates in ET-cells was significantly decreased both at 30s and 600s after VP addition. The distribution of [2-3H]-inositol labeling accumulated in the different inositol phosphate fractions over the first 30s of VP stimulation showed a tendency to lower accumulation of inositol trisphosphate, and a significantly lower accumulation of inositol bisphosphate simultaneously with a higher labeling of the inositol tetrakisphosphate fraction. These observations reflect an early effect of ET-infusion on VP-stimulated inositol lipid turnover and on the subsequent metabolism of the released inositol phosphates

  5. Thermal degradation products of saccharides: effect study over Escherichia coli K12S cells; Produtos de termodegradacao de sacarideos: estudo do efeito sobre celulas de Escherichia coli K12S

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, R.L.B.C. de

    1981-12-31

    The heat sterilization of reducing sugars, in the presence of phosphates, in alkaline pH, promotes caramelization reactions, yielding a serie of degradation products. Among them, aldehyde-like compounds seem to be responsible for the decrease in viability of DNA repair-proficient E.coli cells. A positive interaction between toxic solutions and UV-radiation effects is observed in these cells. The sinergism UV-toxic solutions varies in function of post-irradiation time and is dependent on UV dose, indicating the interference of repair processes in toxicity. The effect of non-reducing sugars on cellular viability is negligible, suggesting that toxic substances generation is linked to the presence of at least a free carbonyl group in sugar structure. All tested reducing sugars, when experimental conditions remained constant, have similarly shaped inactivation kinetics and their effects are equally inhibited by catalase activity, during incubation. (author).

  6. Effects of intramuscularly administered enrofloxacin on the susceptibility of commensal intestinal Escherichia coli in pigs (sus scrofa domestica).

    Science.gov (United States)

    Römer, Antje; Scherz, Gesine; Reupke, Saskia; Meißner, Jessica; Wallmann, Jürgen; Kietzmann, Manfred; Kaspar, Heike

    2017-12-04

    In the European Union, various fluoroquinolones are authorised for the treatment of food producing animals. Each administration poses an increased risk of development and spread of antimicrobial resistance. The aim of this study was to investigate the impact of parenteral administration of enrofloxacin on the prevalence of enrofloxacin and ciprofloxacin susceptibilities in the commensal intestinal E. coli population. E. coli isolates from faeces of twelve healthy pigs were included. Six pigs were administered enrofloxacin on day 1 to 3 and after two weeks for further three days. The other pigs formed the control group. MIC values were determined. Virulence and resistance genes were detected by PCR. Phylogenetic grouping was performed by PCR. Enrofloxacin and ciprofloxacin were analysed in sedimentation samples by HPLC. Susceptibility shifts in commensal E. coli isolates were determined in both groups. Non-wildtype E. coli could be cultivated from two animals of the experimental group for the first time one week after the first administration and from one animal of the control group on day 28. The environmental load with enrofloxacin in sedimentation samples showed the highest amount between days one and five. The repeated parenteral administration of enrofloxacin to pigs resulted in rapidly increased MIC values (day 28: MIC up to 4 mg/L, day 35: MIC ≥ 32mg/L). E. coli populations of the control group in the same stable without direct contact to the experimental group were affected. The parenteral administration of enrofloxacin to piglets considerably reduced the number of the susceptible intestinal E. coli population which was replaced by E. coli strains with increased MIC values against enrofloxacin. Subsequently also pigs of the control were affected suggesting a transferability of strains from the experimental group through the environment to the control group especially as we could isolate the same PFGE strains from both pig groups and the environment.

  7. Killing of Escherichia coli using the gas diffusion electrode system.

    Science.gov (United States)

    Xu, W Y; Li, P; Dong, B

    2010-01-01

    To be best of our knowledge, this study is one of the first investigations to be performed into the potential benefits of gas diffusion electrode (GDE) system in controlling inactivation of E. coli. This study mainly focused on the dual electrodes disinfection with gas diffusion cathode, using Escherichia coli as the indicator microorganisms. The effects of Pt load W(Pt) and the pore-forming agent content W(NH(4)HCO(3)) in GDE, operating conditions such as pH value, oxygen flow rate Q(O(2)), salt content and current density on the disinfection were investigated, respectively. The experimental results showed that the disinfection improved with increasing Pt load W(Pt), but its efficiency at Pt load of 3 per thousand was equivalent to that at Pt load of 4 per thousand. Addition of the pore-forming agent in the appropriate amount improved the disinfection while drop of pH value resulted in the rapid rise of the germicidal efficacy and the disinfection shortened with increasing oxygen flow rate Q(O(2)). The system is more suitable for highly salt water. The germicidal efficacy increased with current density. However, the accelerating rate was different: it first increased with the current density, then decreased, and reached a maximum at current density of 6.7-8.3 mA/cm(2). The germicidal efficacy in the cathode compartment was about the same as in the anode compartment indicating the contribution of direct oxidation and indirect treatment of E. coli by the hydroxyl radical was similar to the oxidative indirect effect of the generated H(2)O(2). This technology is expensive in operating cost, further research is required to advance the understanding and reduce the operating cost of this technology.

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

    Science.gov (United States)

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

    2014-05-27

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

  9. Effect of pH, temperature, and salt on the stability of Escherichia coli- and Chinese hamster ovary cell-derived IgG1 Fc.

    Science.gov (United States)

    Li, Cynthia H; Narhi, Linda O; Wen, Jie; Dimitrova, Mariana; Wen, Zai-qing; Li, Jenny; Pollastrini, Joseph; Nguyen, Xichdao; Tsuruda, Trace; Jiang, Yijia

    2012-12-18

    The circulation half-life of a potential therapeutic can be increased by fusing the molecule of interest (an active peptide, the extracellular domain of a receptor, an enzyme, etc.) to the Fc fragment of a monoclonal antibody. For the fusion protein to be a successful therapeutic, it must be stable to process and long-term storage conditions, as well as to physiological conditions. The stability of the Fc used is critical for obtaining a successful therapeutic protein. The effects of pH, temperature, and salt on the stabilities of Escherichia coli- and Chinese hamster ovary cell (CHO)-derived IgG1 Fc high-order structure were probed using a variety of biophysical techniques. Fc molecules derived from both E. coli and CHO were compared. The IgG1 Fc molecules from both sources (glycosylated and aglycosylated) are folded at neutral pH and behave similarly upon heat- and low pH-induced unfolding. The unfolding of both IgG1 Fc molecules occurs via a multistep unfolding process, with the tertiary structure and C(H)2 domain unfolding first, followed by changes in the secondary structure and C(H)3 domain. The acid-induced unfolding of IgG1 Fc molecules is only partially reversible, with the formation of high-molecular weight species. The CHO-derived Fc protein (glycosylated) is more compact (smaller hydrodynamic radius) than the E. coli-derived protein (aglycosylated) at neutral pH. Unfolding is dependent on pH and salt concentration. The glycosylated C(H)2 domain melts at a temperature 4-5 °C higher than that of the aglycosylated domain, and the low-pH-induced unfolding of the glycosylated Fc molecule occurs at a pH ~0.5 pH unit lower than that of the aglycosylated protein. The difference observed between E. coli- and CHO-derived Fc molecules primarily involves the C(H)2 domain, where the glycosylation of the Fc resides.

  10. The viable but non-culturable state in pathogenic Escherichia coli: A general review

    Directory of Open Access Journals (Sweden)

    Jennifer A. Pienaar

    2016-05-01

    Objectives: This review discusses various general aspects of the VBNC state, the mechanisms and possible public health impact of indicator and pathogenic E. coli entering into the VBNC state. Method: A literature review was conducted to ascertain the possibleimpact of E. coli entering into the VBNC state. Results: Escherichia coli enter into the VBNC state by means of several induction mechanisms. Various authors have found that E. coli can be resuscitated post-VBNC. Certain strains of pathogenic E. coli are still able to produce toxins in the VBNC state, whilst others are avirulent during the VBNC state but are able to regain virulence after resuscitation. Conclusion: Pathogenic and indicator E. coli entering into the VBNC state could have an adverse effect on public health if conventional detection methods are used, where the number of viable cells could be underestimated and the VBNC cells still produce toxins or could, at anytime, be resuscitated and become virulent again.

  11. Evaluation of the efficacy of an autogenous Escherichia coli vaccine in broiler breeders

    DEFF Research Database (Denmark)

    Li, Lili; Thøfner, Ida; Christensen, Jens Peter

    2017-01-01

    vaccine in broiler breeders. Three groups of 28 weeks old broiler breeders (unvaccinated, vaccinated once and twice, respectively) were challenged with a homologous E. coli strain (same strain as included in the vaccine) or a heterologous challenge strain in an experimental ascending model. The clinical...... infection, significant protection of an autogenous E. coli vaccine against neither a homologous nor a heterologous E. coli challenge could not be documented.......In poultry production Escherichia coli autogenous vaccines are often used. However, the efficacy of autogenous E. coli vaccinations has not been evaluated experimentally in chickens after start of lay. The aim of the present study was to evaluate the protective effect of an autogenous E. coli...

  12. High mutation rates limit evolutionary adaptation in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Kathleen Sprouffske

    2018-04-01

    Full Text Available Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli's genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild.

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

    Directory of Open Access Journals (Sweden)

    Werber Dirk

    2012-02-01

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

  14. The effect of sub-minimum inhibitory concentration of ciprofloxacin concentrations on enteroaggregative Escherichia coli and the role of the surface protein dispersin

    Energy Technology Data Exchange (ETDEWEB)

    Mortensen, Ninell P [ORNL; Fowlkes, Jason Davidson [ORNL; Trevino-Dopatka, Sonia [ORNL; Maggart, Michael J [ORNL; Boisen, Nadia [University of Virginia School of Medicine; Doktycz, Mitchel John [ORNL; Nataro, James [University of Virginia School of Medicine; Allison, David P [ORNL

    2011-01-01

    Enteroaggregative Escherichia coli (EAEC) are bacterial pathogens that cause watery diarrhea, which is often persistent and can be inflammatory. The antibiotic ciprofloxacin is used to treat EAEC infections, but a full understanding of the antimicrobial effects of ciprofloxacin is needed for more efficient treatment of bacterial infections. In this study, it was found that sub-minimum inhibitory concentrations (sub-MICs) of ciprofloxacin had an inhibitory effect on EAEC adhesion to glass and mammalian HEp-2 cells. It was also observed that bacterial surface properties play an important role in bacterial sensitivity to ciprofloxacin. In an EAEC mutant strain where the hydrophobic positively charged surface protein dispersin was absent, sensitivity to ciprofloxacin was reduced compared with the wild-type strain. Identified here are several antimicrobial effects of ciprofloxacin at sub-MIC concentrations indicating that bacterial surface hydrophobicity affects the response to ciprofloxacin. Investigating the effects of sub-MIC doses of antibiotics on targeted bacteria could help to further our understanding of bacterial pathogenicity and elucidate future antibiotic treatment modalities.

  15. Effects of sub-minimum inhibitory concentrations of ciprofloxacin on enteroaggregative Escherichia coli and the role of the surface protein dispersin

    Energy Technology Data Exchange (ETDEWEB)

    Fowlkes, Jason Davidson [ORNL; Doktycz, Mitchel John [ORNL; Allison, David Post [ORNL

    2011-01-01

    Enteroaggregative Escherichia coli (EAEC) are bacterial pathogens that cause watery diarrhoea, which is often persistent and can be inflammatory. The antibiotic ciprofloxacin is used to treat EAEC infections, but a full understanding of the antimicrobial effects of ciprofloxacin is needed for more efficient treatment of bacterial infections. In this study, it was found that sub-minimum inhibitory concentrations (sub-MICs) of ciprofloxacin had an inhibitory effect on EAEC adhesion to glass and mammalian HEp-2 cells. It was also observed that bacterial surface properties play an important role in bacterial sensitivity to ciprofloxacin. In an EAEC mutant strain where the hydrophobic positively charged surface protein dispersin was absent, sensitivity to ciprofloxacin was reduced compared with the wild-type strain. Identified here are several antimicrobial effects of ciprofloxacin at sub-MIC concentrations indicating that bacterial surface hydrophobicity affects the response to ciprofloxacin. Investigating the effects of sub-MIC doses of antibiotics on targeted bacteria could help to further our understanding of bacterial pathogenicity and elucidate future antibiotic treatment modalities.

  16. Emergence of Quinolone Resistance amongst Escherichia coli ...

    African Journals Online (AJOL)

    Rate of resistance was 22.3% showing an increase in quinolone resistance when ... FQR E. coli was more common in patients with urinary tract infection (22.9%). ... in the faeces of healthy adults was 22.9%, 6.7% in children and 22.2% in avian. ... thereby aiding the spread of antibiotic resistant strains from avians to human ...

  17. Cellular chain formation in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Klemm, Per

    2009-01-01

    ; type I fimbriae expression significantly reduced cellular chain formation, presumably by steric hindrance. Cellular chain formation did not appear to be specific to E coli K-12. Although many urinary tract infection (UTI) isolates were found to form rather homogeneous, flat biofilms, three isolates...

  18. Genomic Comparative Study of Bovine Mastitis Escherichia coli.

    Science.gov (United States)

    Kempf, Florent; Slugocki, Cindy; Blum, Shlomo E; Leitner, Gabriel; Germon, Pierre

    2016-01-01

    Escherichia coli, one of the main causative agents of bovine mastitis, is responsible for significant losses on dairy farms. In order to better understand the pathogenicity of E. coli mastitis, an accurate characterization of E. coli strains isolated from mastitis cases is required. By using phylogenetic analyses and whole genome comparison of 5 currently available mastitis E. coli genome sequences, we searched for genotypic traits specific for mastitis isolates. Our data confirm that there is a bias in the distribution of mastitis isolates in the different phylogenetic groups of the E. coli species, with the majority of strains belonging to phylogenetic groups A and B1. An interesting feature is that clustering of strains based on their accessory genome is very similar to that obtained using the core genome. This finding illustrates the fact that phenotypic properties of strains from different phylogroups are likely to be different. As a consequence, it is possible that different strategies could be used by mastitis isolates of different phylogroups to trigger mastitis. Our results indicate that mastitis E. coli isolates analyzed in this study carry very few of the virulence genes described in other pathogenic E. coli strains. A more detailed analysis of the presence/absence of genes involved in LPS synthesis, iron acquisition and type 6 secretion systems did not uncover specific properties of mastitis isolates. Altogether, these results indicate that mastitis E. coli isolates are rather characterized by a lack of bona fide currently described virulence genes.

  19. Incidence of Escherichia coli  - Glucuronidase Positive on Goat Milk

    Directory of Open Access Journals (Sweden)

    Zorica Voşgan

    2016-11-01

    Full Text Available Papers on beta- glucuronidase sensitivity and specificity for identifying Escherichia coli in sources of environment, food, water, etc. have been published since 1976. In this study we conducted a review of the incidence of E. coli β- glucuronidase -positive in goat milk, obtained by hand milking throughout the lactation: spring, summer, autumn. The presence of E. coli in milk is considered both as a health indicator and a pathogenic factor capable of causing food poisoning. The determination of the E. coli β-glucuronidase-positive was carried using TBX medium by cultivating colonies typical blue at 440C. The absence of E. coli in milk yielded during the spring, when the animal milking is done three times a day, was found in the performed analyses; the same was observed during fall, when the milk production is lower and the milking is done once a day. The load of E. coli β-glucuronidase-positive was averaging 66.67 CFU/ml of goat milk, during the middle lactation period (July-August, in conditions of higher temperature. During this period, milking is done in the mountain zone, where the transhumance of animals takes place in summer. The presence of the species E. coli was also confirmed by microscopic examination. Attention should be paid to hygiene and milk should be immediately cooled, during hot weather, as E. coli can be a source of food poisoning.

  20. Interaction of Escherichia coli with growing salad spinach plants.

    Science.gov (United States)

    Warriner, Keith; Ibrahim, Faozia; Dickinson, Matthew; Wright, Charles; Waites, William M

    2003-10-01

    In this study, the interaction of a bioluminescence-labeled Escherichia coli strain with growing spinach plants was assessed. Through bioluminescence profiles, the direct visualization of E. coli growing around the roots of developing seedlings was accomplished. Subsequent in situ glucuronidase (GUS) staining of seedlings confirmed that E. coli had become internalized within root tissue and, to a limited extent, within hypocotyls. When inoculated seeds were sown in soil microcosms and cultivated for 42 days, E. coli was recovered from the external surfaces of spinach roots and leaves as well as from surface-sterilized roots. When 20-day-old spinach seedlings (from uninoculated seeds) were transferred to soil inoculated with E. coli, the bacterium became established on the plant surface, but internalization into the inner root tissue was restricted. However, for seedlings transferred to a hydroponic system containing 10(2) or 10(3) CFU of E. coli per ml of the circulating nutrient solution, the bacterium was recovered from surface-sterilized roots, indicating that it had been internalized. Differences between E. coli interactions in the soil and those in the hydroponic system may be attributed to greater accessibility of the roots in the latter model. Alternatively, the presence of a competitive microflora in soil may have restricted root colonization by E. coli. The implications of this study's findings with regard to the microbiological safety of minimally processed vegetables are discussed.

  1. Effects of Lactobacillus kefiranofaciens M1 isolated from kefir grains on enterohemorrhagic Escherichia coli infection using mouse and intestinal cell models.

    Science.gov (United States)

    Chen, Y P; Lee, T Y; Hong, W S; Hsieh, H H; Chen, M J

    2013-01-01

    A potential probiotic strain, Lactobacillus kefiranofaciens M1, was previously isolated from kefir grains, which are used to manufacture the traditional fermented drink kefir. The aim of this study was to investigate the effects of Lb. kefiranofaciens M1 on enterohemorrhagic Escherichia coli (EHEC) infection, using mice and intestinal cell models. BALB/c mice were daily administrated with either phosphate buffered saline or Lb. kefiranofaciens M1 at 2×10(8) cfu/mouse per day intragastrically for 7 d. Intragastric challenges with EHEC (2×10(9) cfu/mouse) were conducted on d 0, 4, and 7 after treatment. Administration of Lb. kefiranofaciens M1 was able to prevent EHEC infection-induced symptoms, intestinal damage, renal damage, bacterial translocation, and Shiga toxin penetration. Furthermore, the mucosal EHEC-specific IgA responses were increased after Lb. kefiranofaciens M1 administration in the EHEC-infected mouse system. Additionally, in vitro, Lb. kefiranofaciens M1 was shown to have a protective effect on Caco-2 intestinal epithelial cells and Caco-2 intestinal epithelial cell monolayers; the bacteria limited EHEC-induced cell death and reduced the loss of epithelial integrity. These findings support the potential of Lb. kefiranofaciens M1 treatment as an approach to preventing EHEC infection and its effects. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  2. Effect of frequency and waveform on inactivation of Escherichia coli O157:H7 and Salmonella enterica Serovar Typhimurium in salsa by ohmic heating.

    Science.gov (United States)

    Lee, Su-Yeon; Ryu, Sangryeol; Kang, Dong-Hyun

    2013-01-01

    The effect of frequency of alternating current during ohmic heating on electrode corrosion, heating rate, inactivation of food-borne pathogens, and quality of salsa was investigated. The impact of waveform on heating rate was also investigated. Salsa was treated with various frequencies (60 Hz to 20 kHz) and waveforms (sine, square, and sawtooth) at a constant electric field strength of 12.5 V/cm. Electrode corrosion did not occur when the frequency exceeded 1 kHz. The heating rate of the sample was dependent on frequency up to 500 Hz, but there was no significant difference (P > 0.05) in the heating rate when the frequency was increased above 1 kHz. The electrical conductivity of the sample increased with a rise in the frequency. At a frequency of 60 Hz, the square wave produced a lower heating rate than that of sine and sawtooth waves. The heating rate between waveforms was not significantly (P > 0.05) different when the frequency was >500 Hz. As the frequency increased, the treatment time required to reduce Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium to below the detection limit (1 log CFU/g) decreased without affecting product quality. These results suggest that ohmic heating can be effectively used to pasteurize salsa and that the effect of inactivation is dependent on frequency and electrical conductivity rather than waveform.

  3. Chromosomal features of Escherichia coli serotype O2:K2, an avian pathogenic E. coli.

    Science.gov (United States)

    Jørgensen, Steffen L; Kudirkiene, Egle; Li, Lili; Christensen, Jens P; Olsen, John E; Nolan, Lisa; Olsen, Rikke H

    2017-01-01

    Escherichia coli causing infection outside the gastrointestinal system are referred to as extra-intestinal pathogenic E. coli. Avian pathogenic E. coli is a subgroup of extra-intestinal pathogenic E. coli and infections due to avian pathogenic E. coli have major impact on poultry production economy and welfare worldwide. An almost defining characteristic of avian pathogenic E. coli is the carriage of plasmids, which may encode virulence factors and antibiotic resistance determinates. For the same reason, plasmids of avian pathogenic E. coli have been intensively studied. However, genes encoded by the chromosome may also be important for disease manifestation and antimicrobial resistance. For the E. coli strain APEC_O2 the plasmids have been sequenced and analyzed in several studies, and E. coli APEC_O2 may therefore serve as a reference strain in future studies. Here we describe the chromosomal features of E. coli APEC_O2. E. coli APEC_O2 is a sequence type ST135, has a chromosome of 4,908,820 bp (plasmid removed), comprising 4672 protein-coding genes, 110 RNA genes, and 156 pseudogenes, with an average G + C content of 50.69%. We identified 82 insertion sequences as well as 4672 protein coding sequences, 12 predicated genomic islands, three prophage-related sequences, and two clustered regularly interspaced short palindromic repeats regions on the chromosome, suggesting the possible occurrence of horizontal gene transfer in this strain. The wildtype strain of E. coli APEC_O2 is resistant towards multiple antimicrobials, however, no (complete) antibiotic resistance genes were present on the chromosome, but a number of genes associated with extra-intestinal disease were identified. Together, the information provided here on E. coli APEC_O2 will assist in future studies of avian pathogenic E. coli strains, in particular regarding strain of E. coli APEC_O2, and aid in the general understanding of the pathogenesis of avian pathogenic E. coli .

  4. Alterations induced in Escherichia Coli cells by gamma radiation

    International Nuclear Information System (INIS)

    Kappke, J.; Schelin, H.R.; Paschuk, S.A.; Denyak, V.; Silva, E.R. da; Jesus, E.F.O. de; Lopes, R.T.; Carlin, N.; Toledo, E.S.

    2007-01-01

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

  5. Effect of Temperature on the Survival of F-Specific RNA Coliphage, Feline Calicivirus, and Escherichia coli in Chlorinated Water

    Directory of Open Access Journals (Sweden)

    Sagar M. Goyal

    2005-12-01

    Full Text Available We compared the survival of F-specific RNA coliphage MS2, feline calicivirus, and E. coli in normal tap water and in tap water treated to an initial concentration of 50 ppm free chlorine and held at 4°C, 25°C, or 37°C for up to 28 days. Our aim was to determine which of these two organisms (coliphage or E. coli was better at indicating norovirus survival under the conditions of the experiment. There was a relatively rapid decline of FCV and E. coli in 50 ppm chlorine treated water and both organisms were undetectable within one day irrespective of the temperature. In contrast, FRNA phage survived for 7 to 14 days in 50 ppm chlorine treated water at all temperatures. All organisms survived for 28 days in tap water at 4°C, but FCV was undetectable on day 21 and day 7 at 25°C and 37°C, respectively. Greater survival of FRNA phage compared to E. coli in 50 ppm chlorine treated water suggests that these organisms should be further investigated as indicators of norovirus in depurated shellfish, sanitized produce, and treated wastewater which are all subject to high-level chlorine treatment.

  6. Antimicrobial effects of zero-valent iron nanoparticles on gram-positive Bacillus strains and gram-negative Escherichia coli strains

    Directory of Open Access Journals (Sweden)

    Yi-Huang Hsueh

    2017-11-01

    Full Text Available Abstract Background Zero-valent iron nanoparticles (ZVI NPs have been used extensively for the remediation of contaminated soil and groundwater. Owing to their large active surface area, they serve as strong and effective reductants. However, the ecotoxicity and bioavailability of ZVI NPs in diverse ecological media have not been evaluated in detail and most studies have focused on non-nano ZVI or Fe0. In addition, the antimicrobial properties of ZVI NPs have rarely been investigated, and the underlying mechanism of their toxicity remains unknown. Results In the present study, we demonstrate that ZVI NPs exhibited significant toxicity at 1000 ppm against two distinct gram-positive bacterial strains (Bacillus subtilis 3610 and Bacillus thuringiensis 407 but not against two gram-negative strains (Escherichia coli K12 and ATCC11634. Specifically, ZVI NPs caused at least a 4-log and 1-log reductions in cell numbers, respectively, in the two Bacillus strains, whereas no change was detected in the two E. coli strains. X-ray photoelectron spectroscopy, X-ray absorption near-edge, and extended X-ray absorption fine structure spectra confirmed that Bacillus cells exposed to ZVI NPs contained mostly Fe2O3 with some detectable FeS. This finding indicated that Fe0 nanoparticles penetrated the bacterial cells, where they were subsequently oxidized to Fe2O3 and FeS. RedoxSensor analysis and propidium iodide (PI staining showed decreased reductase activity and increased PI in both Bacillus strains treated with a high (1000 ppm concentration of ZVI NPs. Conclusion Taken together, these data show that the toxicity of ZVI NPs was derived from their oxidative properties, which may increase the levels of reactive oxygen species and lead to cell death.

  7. Intestinal Anti-inflammatory Effects of Outer Membrane Vesicles from Escherichia coli Nissle 1917 in DSS-Experimental Colitis in Mice

    Directory of Open Access Journals (Sweden)

    María-José Fábrega

    2017-07-01

    Full Text Available Escherichia coli Nissle 1917 (EcN is a probiotic strain with proven efficacy in inducing and maintaining remission of ulcerative colitis. However, the microbial factors that mediate these beneficial effects are not fully known. Gram-negative bacteria release outer membrane vesicles (OMVs as a direct pathway for delivering selected bacterial proteins and active compounds to the host. In fact, vesicles released by gut microbiota are emerging as key players in signaling processes in the intestinal mucosa. In the present study, the dextran sodium sulfate (DSS-induced colitis mouse model was used to investigate the potential of EcN OMVs to ameliorate mucosal injury and inflammation in the gut. The experimental protocol involved pre-treatment with OMVs for 10 days before DSS intake, and a 5-day recovery period. Oral administration of purified EcN OMVs (5 μg/day significantly reduced DSS-induced weight loss and ameliorated clinical symptoms and histological scores. OMVs treatment counteracted altered expression of cytokines and markers of intestinal barrier function. This study shows for the first time that EcN OMVs can mediate the anti-inflammatory and barrier protection effects previously reported for this probiotic in experimental colitis. Remarkably, translation of probiotics to human healthcare requires knowledge of the molecular mechanisms involved in probiotic–host interactions. Thus, OMVs, as a non-replicative bacterial form, could be explored as a new probiotic-derived therapeutic approach, with even lower risk of adverse events than probiotic administration.

  8. Effectiveness of superheated steam for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, Salmonella Enteritidis phage type 30, and Listeria monocytogenes on almonds and pistachios.

    Science.gov (United States)

    Ban, Ga-Hee; Kang, Dong-Hyun

    2016-03-02

    This study was undertaken to evaluate the effectiveness of superheated steam (SHS) on the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, Salmonella Enteritidis phage type (PT) 30 and Listeria monocytogenes on almonds and in-shell pistachios and to determine the effect of superheated steam heating on quality by measuring color and texture changes. Almonds and in-shell pistachios inoculated with four foodborne pathogens were treated with saturated steam (SS) at 100 °C and SHS at 125, 150, 175, and 200 °C for various times. Exposure of almonds and pistachios to SHS for 15 or 30s at 200 °C achieved >5l og reductions among all tested pathogens without causing significant changes in color values or texture parameters (P>0.05). For both almonds and pistachios, acid and peroxide values (PV) following SS and SHS treatment for up to 15s and 30s, respectively, were within the acceptable range (PV<1.0 meq/kg). These results show that thermal application of 200 °C SHS treatment for 15s and 30s did not affect the quality of almonds and pistachios, respectively. Therefore, SHS treatment is a very promising alternative technology for the tree nuts industry by improving inactivation of foodborne pathogens on almonds and pistachios while simultaneously reducing processing time. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Mechanisms of the adjuvant effect of hemoglobin in experimental peritonitis. VII. Hemoglobin does not inhibit clearance of Escherichia coli from the peritoneal cavity

    International Nuclear Information System (INIS)

    Dunn, D.L.; Barke, R.A.; Lee, J.T. Jr.; Condie, R.M.; Humphrey, E.W.; Simmons, R.L.

    1983-01-01

    Hemoglobin has been shown to be a potent adjuvant in experimental Escherichia coli peritonitis, although a satisfactory mechanistic rationale is still obscure. Hemoglobin has been thought to impair intraperitoneal neutrophil function, delay clearance of bacteria from the peritoneal cavity by the normal absorptive mechanisms, or directly enhance bacterial growth. Using highly purified stroma-free hemoglobin (SFHgb), we have largely discounted any direct effect of hemoglobin on peritoneal white blood cell function. In the present study, we confirmed that uncontrolled proliferation of bacteria takes place in the presence of hemoglobin in the peritoneal cavity. Nonviable 5-iododeoxyuridine 125 I-labelled bacteria were then used to directly study peritoneal clearance kinetics, eliminating the problem of bacterial growth. SFHgb had no influence on the removal of intraperitoneal bacteria. The rate of bloodstream appearance of radiolabel was similar with or without intraperitoneal SFHgb. Thus, SFHgb does not prevent clearance of bacteria from the peritoneal cavity by interfering with normal host clearance mechanisms. SFHgb may act as a bacterial growth adjuvant, either by serving as a bacterial nutrient or by suitably modifying the environment so that extensive bacterial proliferation can occur. The latter hypothesis appears to be an area in which investigation concerning the adjuvant effect of hemoglobin may prove most fruitful

  10. Expression, purification, and characterization of a dentin phosphoprotein produced by Escherichia coli, and its odontoblastic differentiation effects on human dental pulp cells.

    Science.gov (United States)

    Yun, Ye-Rang; Jeon, Eunyi; Lee, Sujin; Kang, Wonmo; Kim, Sang-Gi; Kim, Hae-Won; Suh, Chang Kook; Jang, Jun-Hyeog

    2012-08-01

    To investigate the functions of recombinant human dentin phosphoprotein (rhDPP), we examined cell adhesion, viability and the odontoblastic differentiation activity of human dental pulp cells (hDPCs). Firstly, rhDPP was constructed using pBAD-HisA plasmid in Escherichia coli. Cell adhesion and viability of hDPCs by rhDPP was examined using a crystal violet assay and a MTT assay, ALP, mineralization activity and odontoblastic differentiation-related mRNA levels of hDPCs were measured to elucidate the odontoblastic differentiation effect of rhDPP on hDPCs. Initially, rhDPP significantly and dose-dependently increased hDPCs adhesion versus the untreated control (p < 0.05). Cell viability was also significantly increased by rhDPP at 5 days (p < 0.001). Furthermore, the odontoblastic differentiation effect of rhDPP was verified by measuring ALP activity, mineralization activity and the mRNA levels of odontoblastic differentiation markers. Taken together, rhDPP is expected to play an important role on hDPCs, thereby suggesting its potential use for tooth repair and regeneration.

  11. Temperature sensitivity of the penicillin-induced autolysis mechanism in nongrowing cultures of Escherichia coli.

    OpenAIRE

    Kusser, W; Ishiguro, E E

    1987-01-01

    The effect of incubation temperature on the ampicillin-induced autolysis of nongrowing Escherichia coli was determined. The autolysis mechanisms in amino acid-deprived relA mutant cells treated with chloramphenicol were temperature sensitive. This temperature-sensitive autolysis was demonstrated in three independent ways: turbidimetric determinations, viable cell counts, and solubilization of radiolabeled peptidoglycan.

  12. Fermented soya bean (tempe) extracts reduce adhesion of enterotoxigenic Escherichia coli to intestinal epithelial cells

    NARCIS (Netherlands)

    Roubos-van den Hil, P.J.; Nout, M.J.R.; Beumer, R.R.; Meulen, van der J.; Zwietering, M.H.

    2009-01-01

    Aims: This study aimed to investigate the effect of processed soya bean, during the successive stages of tempe fermentation and different fermentation times, on adhesion of enterotoxigenic Escherichia coli (ETEC) K88 to intestinal brush border cells as well as Caco-2 intestinal epithelial cells; and

  13. Ciprofloxacin and probiotic Escherichia coli Nissle add-on treatment in active ulcerative colitis

    DEFF Research Database (Denmark)

    Petersen, Andreas Munk; Mirsepasi, Hengameh; Halkjær, Sofie Ingdam

    2014-01-01

    BACKGROUND AND AIM: Ulcerative colitis (UC) is a chronic inflammatory bowel disease. The probiotic bacterium Escherichia coli Nissle 1917 (EcN) has been used to maintain and induce clinical remission in UC. Our aim was to test the effect of Ciprofloxacin and/or orally administered EcN as add...

  14. Incapacity of β - carotene to protect Escherichia coli J-5 against ultra violet lethal action

    International Nuclear Information System (INIS)

    Passos Junior, G.A.S.; Zucchi, T.M.A.D.

    1982-01-01

    The ultra violet light survival of Escherichia coli J-5 cell population was not modified when it was β-carotene treated. It was found that this carotenoid does not confer radioprotection to the u.v. light effects in this bacterial strain. (author) [pt

  15. [Antibacterial actin of vinegar against food-borne pathogenic bacteria including Escherichia coli O157:H7 (Part 2). Effect of sodium chloride and temperature on bactericidal activity].

    Science.gov (United States)

    Entani, E; Asai, M; Tsujihata, S; Tsukamoto, Y; Ohta, M

    1997-05-01

    Bactericidal effects of various kinds of AWASEZU (processed vinegar, 2.5% acidity) on food-borne pathogenic bacteria including Escherichia coli O157:H7 and other bacteria were examined. the order of bactericidal activities was NIHAIZU (3.5% NaCl was added) > SANBA-IZU (3.5% NaCl and 10% sucrose were added) > plain vinegar (spirit vinegar) > AMAZU (10% sucrose was added). This indicates that their activities were enhanced by the addition of sodium chloride and suppressed by the addition of sugar. On the other hand, when soy sauce was used instead of sodium chloride, the order of bactericidal activities was plain vinegar > AMAZU > NIHAIZU > SANBAIZU. This is mainly because their activities were suppressed by the increase in the pH value. The effect of sodium chloride (0.01-15%) and temperature (10-50 degrees C) on bactericidal activities against E. coli O157:H7 in spirit vinegar (0.5-2.5% acidity) was further examined. When vinegar was used in combination with sodium chloride, predominant synergism on the bactericidal activity was observed. Their activities were markedly enhanced by the addition of sodium chloride in proportion to the concentration. In addition to this, at higher temperatures spirit vinegar killed bacteria much more rapidly. It should be noted that the bactericidal activity of spirit vinegar was extremely enhanced by the combined use of the addition of sodium chloride and the rise of temperature. For example, in 2.5% acidity vinegar, the time required for 3 log decrease in viable cell numbers at 20 degrees C was shortened to 1/140-fold by the addition of 5% sodium chloride, shortened to 1/51-fold by the rise of the reaction temperature at 40 degrees C, and shortened to 1/830-fold; 0.89 minutes by both the addition of 5% sodium chloride and the rise of temperature at 40 degrees C. In order to propose the methods to prevent food poisoning by bacterial infection, bactericidal activities of vinegar solution containing sodium chloride on cooking tools and

  16. Overexpression and surface localization of the Chlamydia trachomatis major outer membrane protein in Escherichia coli

    DEFF Research Database (Denmark)

    Koehler, JF; Birkelund, Svend; Stephens, RS

    1992-01-01

    The Chlamydia trachomatis major outer membrane protein (MOMP) is the quantitatively predominant surface protein which has important functional, structural and antigenic properties. We have cloned and overexpressed the MOMP in Escherichia coli. The MOMP is surface exposed in C. trachomatis....... The induction of MOMP expression had a rapidly lethal effect on the L2rMOMP E. coli clone. Although no genetic system exists for Chlamydia, development of a stable, inducible E. coli clone which overexpresses the chlamydial MOMP permits a study of the biological properties of the MOMP, including...

  17. Novel roles for the AIDA adhesin from diarrheagenic Escherichia coli:

    DEFF Research Database (Denmark)

    Sherlock, Orla; Schembri, Mark; Reisner, A.

    2004-01-01

    Diarrhea-causing Escherichia coli strains are responsible for numerous cases of gastrointestinal disease and constitute a serious health problem throughout the world. The ability to recognize and attach to host intestinal surfaces is an essential step in the pathogenesis of such strains. AIDA...... binds to mammalian cells. Here, we show that AIDA possesses self-association characteristics and can mediate autoaggregation of E. coli cells. We demonstrate that intercellular AIDA-AIDA interaction is responsible for bacterial autoaggregation. Interestingly, AIDA-expressing cells can interact...

  18. DNA microarray analysis of fim mutations in Escherichia coli

    DEFF Research Database (Denmark)

    Schembri, Mark; Ussery, David; Workman, Christopher

    2002-01-01

    Bacterial adhesion is often mediated by complex polymeric surface structures referred to as fimbriae. Type I fimbriae of Escherichia coli represent the archetypical and best characterised fimbrial system. These adhesive organelles mediate binding to D-mannose and are directly associated...... we have used DNA microarray analysis to examine the molecular events involved in response to fimbrial gene expression in E. coli K-12. Observed differential expression levels of the fim genes were in good agreement with our current knowledge of the stoichiometry of type I fimbriae. Changes in fim...

  19. UV irradiation alters deoxynucleoside triphosphate pools in Escherichia coli

    International Nuclear Information System (INIS)

    Das, S.K.; Loeb, L.A.

    1984-01-01

    UV irradiation of exponentially growing Escherichia coli increased intracellular concentration of dATP and dTTP without significantly changing the concentrations of dGTP and dCTP. These selective increases in dATP and dTTP pools are seen in wild-type E. coli K12 and AB1157, as well as in recA and umuC strains, and are proportional to UV dose. The possible significance of these findings with respect to induction of the SOS response and nontargeted mutagenesis are discussed. (orig.)

  20. Genes and proteins of Escherichia coli (GenProtEc).

    Science.gov (United States)

    Riley, M; Space, D B

    1996-01-01

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