scholarly journals Genome sequence and characterisation of coliphage vB_Eco_SLUR29

2019 ◽  
Author(s):  
Ibrahim Besler ◽  
Pavelas Sazinas ◽  
Christian Harrison ◽  
Lucy Gannon ◽  
Tamsin Redgwell ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transmission Electron Microscopy ◽  
Phylogenetic Analysis ◽  
Comparative Genomics ◽  
New Genus ◽  
Multiplicity Of Infection ◽  
Cattle Slurry ◽  
Transmission Electron ◽  
Rural England

AbstractBacteriophage that infect Escherichia coli are relatively easily isolated, with greater than 600 coliphage genomes sequenced to date. Despite this there is still much to be discovered about the diversity of coliphage genomes. Within this study we isolated a coliphage from cattle slurry collected from a farm in rural England. Transmission electron microscopy identified the phage as member of the Siphoviridae family. Phylogenetic analysis and comparative genomics further placed it within the subfamily Tunavirinae and forms part of a new genus. Characterisation of the lytic properties reveals that it is rapidly able to lyse its host when infected at high multiplicity of infection, but not at low multiplicity of infection.

Screening of Condensed Tannins from Canadian Prairie Forages for Anti–Escherichia coli O157:H7 with an Emphasis on Purple Prairie Clover (Dalea purpurea Vent)†

2013 ◽  
Vol 76 (4) ◽  
pp. 560-567 ◽  
Author(s):  
Y. WANG ◽  
L. JIN ◽  
K. H. OMINSKI ◽  
M. HE ◽  
Z. XU ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transmission Electron Microscopy ◽  
Condensed Tannins ◽  
Brown Seaweed ◽  
Coli Strain ◽  
Escherichia Coli O157 ◽  
Canadian Prairie ◽  
E Coli ◽  
Transmission Electron

Tannins from forages grown (n = 10) on the Canadian prairie, as well as from Quebracho, Rhus semialata, and brown seaweed (Ascophyllum nodosum), were screened for anti–Escherichia coli O157:H7 activity against E. coli O157:H7 strain 3081 at a concentration of 400 μg/ml for each tannin type, except for brown seaweed, which was at 50 μg/ml. Growth of the bacteria was assessed by measuring the optical density at 600 nm over 24 h. Tannin from seaweed at a concentration of 50 μg/ml inhibited growth of strain 3081. Among the terrestrial forages, only condensed tannins (CT) from purple prairie clover (Dalea purpurea Vent; PPC) increased (P < 0.05) the lag time and reduced (P < 0.05) the growth rate of E. coli O157:H7. The anti–E. coli O157:H7 activity of PPC CT was further assessed by culturing E. coli strain ATCC 25922 and eight strains of E. coli O157:H7 with PPC CT at 0, 25, 50, 100, or 200 μg/ml. Selected strains were enumerated after 0, 6, and 24 h of incubation, and fatty acid composition was determined after 24 h of incubation. E. coli strain 25922 was cultured with 0, 50, or 200 μg of CT per ml and harvested during the exponential growth phase for examination by transmission electron microscopy. Increasing CT concentration linearly increased (P < 0.001) the lag times of seven strains and linearly reduced (P < 0.001) the growth rates of eight E. coli O157:H7 strains. Proportions of unsaturated fatty acids in the total fatty acids were decreased (P < 0.01) by CT at 50 μg/ml. Transmission electron microscopy showed that CT disrupted the outer membrane structure. Anti–E. coli O157:H7 activity of PPC CT at levels of up to 200 μg/ml was bacteriostatic rather than bactericidal, and the mechanism of anti–E. coli activity may involve alteration in the fatty acid composition and disruption of the outer membrane of the cell.

scholarly journals The Structure of Escherichia coli Signal Recognition Particle Revealed by Scanning Transmission Electron Microscopy

2006 ◽  
Vol 17 (12) ◽  
pp. 5063-5074 ◽  
Author(s):  
Iain L. Mainprize ◽  
Daniel R. Beniac ◽  
Elena Falkovskaia ◽  
Robert M. Cleverley ◽  
Lila M. Gierasch ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transmission Electron Microscopy ◽  
Signal Recognition Particle ◽  
Resonance Energy ◽  
Trigger Factor ◽  
Dimensional Structure ◽  
Signal Recognition ◽  
Transmission Electron ◽  
Nascent Chain

Structural studies on various domains of the ribonucleoprotein signal recognition particle (SRP) have not converged on a single complete structure of bacterial SRP consistent with the biochemistry of the particle. We obtained a three-dimensional structure for Escherichia coli SRP by cryoscanning transmission electron microscopy and mapped the internal RNA by electron spectroscopic imaging. Crystallographic data were fit into the SRP reconstruction, and although the resulting model differed from previous models, they could be rationalized by movement through an interdomain linker of Ffh, the protein component of SRP. Fluorescence resonance energy transfer experiments determined interdomain distances that were consistent with our model of SRP. Docking our model onto the bacterial ribosome suggests a mechanism for signal recognition involving interdomain movement of Ffh into and out of the nascent chain exit site and suggests how SRP could interact and/or compete with the ribosome-bound chaperone, trigger factor, for a nascent chain during translation.

scholarly journals Comparison in Gnotobiotic Pigs of Lesions Caused by Verotoxigenic and Non-verotoxigenic Escherichia coli

1988 ◽  
Vol 25 (3) ◽  
pp. 205-210 ◽  
Author(s):  
G. A. Hall ◽  
N. Chanter ◽  
A. P. Bland
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transmission Electron Microscopy ◽  
Intestinal Tissue ◽  
E Coli ◽  
Histological Sections ◽  
Transmission Electron ◽  
Colony Forming Units ◽  
Gnotobiotic Pigs

To compare the pathogenesis of calf and rabbit strains of E. coli. gnotobiotic pigs were infected with 1010 colony forming units (cfu) of verotoxigenic strain RDEC-1 or S102-9, or a non-verotoxigenic E. coli (X114/83). Pigs were killed 4 days later, and intestinal tissue was fixed and examined by light, scanning, and transmission electron microscopy. Strains S102-9 and RDEC-1 caused diarrhea, attached to enterocytes, and effaced microvilli, confirming that the calf and rabbit strains possessed similar mechanisms of pathogenicity. Non-verotoxigenic strain X114/83 did not cause diarrhea, but in 5/5 piglets it was detected in histological sections adherent to enterocyte surfaces. Exfoliated enterocytes were seen in 4/5. Bacteria attached to enterocytes by “cups” and “pedestals,” with effacement of microvilli, were seen by electron microscopy in 1/5 piglets. It was concluded that strain S102-9 appears to be an animal equivalent of human enterohemorrhagic E. coli. that verotoxin is not essential in the pathogenesis of attaching and effacing lesions, and that the lesions induced by S102-9 are more severe in gnotobiotic pigs than in gnotobiotic or conventional calves.

scholarly journals Structure-Function Relationship of Antibacterial Synthetic Peptides Homologous to a Helical Surface Region on Human Lactoferrin against Escherichia coli Serotype O111

1998 ◽  
Vol 66 (6) ◽  
pp. 2434-2440 ◽  
Author(s):  
Daniel S. Chapple ◽  
David J. Mason ◽  
Christopher L. Joannou ◽  
Edward W. Odell ◽  
Vanya Gant ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transmission Electron Microscopy ◽  
Flow Cytometry ◽  
Antibacterial Activity ◽  
Synthetic Peptides ◽  
Membrane Integrity ◽  
E Coli ◽  
Transmission Electron ◽  
Helical Region

ABSTRACT Lactoferricin includes an 11-amino-acid amphipathic alpha-helical region which is exhibited on the outer surface of the amino-terminal lobe of lactoferrin. Synthetic peptides homologous to this region exhibited potent antibacterial activity against a selected range of both gram-negative and gram-positive bacteria. An analog synthesized with methionine substituted for proline at position 26, which is predicted to disrupt the helical region, abolished antibacterial activity against Escherichia coli and considerably reduced antibacterial activity against Staphylococcus aureus and anAcinetobacter strain. The mode of action of human lactoferrin peptide (HLP) 2 against E. coli serotype O111 (NCTC 8007) was established by using flow cytometry, surface plasmon resonance, and transmission electron microscopy. Flow cytometry was used to monitor membrane potential, membrane integrity, and metabolic processes by using the fluorescent probes bis-1,3-(dibutylbarbituric acid)-trimethine oxonol, propidium iodide, and carbonyl cyanide m-chlorophenylhydrazone, respectively. HLP 2 was found to act at the cell membrane, causing complete loss of membrane potential after 10 min and of membrane integrity within 30 min, with irreversible damage to the cell as shown by rapid loss of viability. The number of particles, measured by light scatter on the flow cytometer, dropped significantly, showing that bacterial lysis resulted. The peptide was shown to bind toE. coli O111 lipopolysaccharide by using surface plasmon resonance. Transmission electron microscopy revealed bacterial distortion, with the outer membrane becoming detached from the inner cytoplasmic membrane. We conclude that HLP 2 causes membrane disruption of the outer membrane, resulting in lysis, and that structural considerations are important for antibacterial activity.

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