Effect of ozone on prophage induction in different strains of Escherichia coli K-12 lysogenic for lambda

1984 ◽  
Vol 26 (6) ◽  
pp. 706-709 ◽  
Author(s):  
Pierre L'Hérault ◽  
Young Sup Chung
Keyword(s):  
Escherichia Coli ◽  
Ultraviolet Light ◽  
Lytic Cycle ◽  
Prophage Induction ◽  
E Coli ◽  
Different Strains ◽  
K 12 ◽  
Lambda Prophage

Ozone was tested for its effect upon induction of lambda prophage in two different strains of Escherichia coli K-12. Based on the induction index and when compared to ultraviolet light, ozone appeared to be a weak, if any at all, inducer of the lytic cycle in E. coli. This is in agreement with other studies which have suggested that this agent is a weak inducer of the SOS functions.Key words: SOS functions, ultraviolet light, mutagen, ozone.

scholarly journals Chromosomal Dynamism in Progeny of Outbreak-Related Sorbitol-Fermenting Enterohemorrhagic Escherichia coli O157:NM

2006 ◽  
Vol 72 (3) ◽  
pp. 1900-1909 ◽  
Author(s):  
Martina Bielaszewska ◽  
Rita Prager ◽  
Wenlan Zhang ◽  
Alexander W. Friedrich ◽  
Alexander Mellmann ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Outbreak Strain ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Uremic Syndrome ◽  
Sporadic Cases ◽  
Different Strains ◽  
K 12

ABSTRACT Sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157:NM (nonmotile) is a unique clone that causes outbreaks of hemorrhagic colitis and hemolytic-uremic syndrome. In well-defined clusters of cases, we have observed significant variability in pulsed-field gel electrophoresis (PFGE) patterns which could indicate coinfection by different strains. An analysis of randomly selected progeny colonies of an outbreak strain after subcultivation demonstrated that they displayed either the cognate PFGE outbreak pattern or one of four additional patterns and were <89% similar. These profound alterations were associated with changes in the genomic position of one of two Shiga toxin 2-encoding genes (stx 2) in the outbreak strain or with the loss of this gene. The two stx 2 alleles in the outbreak strain were identical but were flanked with phage-related sequences with only 77% sequence identity. Neither of these phages produced plaques, but one lysogenized E. coli K-12 and integrated in yecE in the lysogens and the wild-type strain. The presence of two stx 2 genes which correlated with increased production of Stx2 in vitro but not with the clinical outcome of infection was also found in 14 (21%) of 67 SF EHEC O157:NM isolates from sporadic cases of human disease. The variability of PFGE patterns for the progeny of a single colony must be considered when interpreting PFGE patterns in SF EHEC O157-associated outbreaks.

BOUND WATER, INOSITOL, AND THE INDUCTION OF LAMBDA PROPHAGES BY ULTRAVIOLET LIGHT

1967 ◽  
Vol 13 (3) ◽  
pp. 303-312 ◽  
Author(s):  
S. J. Webb ◽  
M. D. Dumasia
Keyword(s):  
Escherichia Coli ◽  
Ultraviolet Light ◽  
Uv Irradiation ◽  
Maximum Rate ◽  
Bound Water ◽  
Water Molecules ◽  
Prophage Induction ◽  
E Coli ◽  
Escherichia Coli K12 ◽  
Uv Dose

Lysogenic cells of Escherichia coli K12 (λ+) and Escherichia coli M3 (λ59) were held in atmospheres having relative humidities (R.H.) from 30% to 80% and irradiated with 2537 Å ultraviolet light (uv.). The colony-forming ability of both types of cell was destroyed more rapidly at 55% R.H. than at any other level of R.H. With E. coli K12 (λ+) the percentage of cells in which prophage induction occurred increased as the dose of ultraviolet light increased and the maximum number of inductions occurred at 55% R.H. Inositol prevented (λ+) prophage induction but was less effective in doing so at 55% R.H. Desiccation alone induced the (λ59) prophage and subsequent uv. irradiation resulted in the destruction of the prophage. The maximum rate of destruction was found at 55% R.H. Inositol prevented the uv. inactivation of the (λ59) prophage, resulting in an increase in inductions with uv. dose at 30% R.H. The free phages were found to have the same sensitivity to ultraviolet light as the induced prophages but were less protected by inositol.It is proposed that water molecules hold the prophage to or in the host DNA and that ultraviolet light induces the prophage and destroys its integrity by reorientating these water molecules.

scholarly journals The CI Repressors of Shiga Toxin-Converting Prophages Are Involved in Coinfection of Escherichia coli Strains, Which Causes a Down Regulation in the Production of Shiga Toxin 2

2008 ◽  
Vol 190 (13) ◽  
pp. 4722-4735 ◽  
Author(s):  
R. Serra-Moreno ◽  
J. Jofre ◽  
M. Muniesa
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Antibiotic Resistance Gene ◽  
Vero Cells ◽  
Toxin Production ◽  
Lytic Cycle ◽  
Host Chromosome ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
K 12

ABSTRACT Shiga toxins (Stx) are the main virulence factors associated with a form of Escherichia coli known as Shiga toxin-producing E. coli (STEC). They are encoded in temperate lambdoid phages located on the chromosome of STEC. STEC strains can carry more than one prophage. Consequently, toxin and phage production might be influenced by the presence of more than one Stx prophage on the bacterial chromosome. To examine the effect of the number of prophages on Stx production, we produced E. coli K-12 strains carrying either one Stx2 prophage or two different Stx2 prophages. We used recombinant phages in which an antibiotic resistance gene (aph, cat, or tet) was incorporated in the middle of the Shiga toxin operon. Shiga toxin was quantified by immunoassay and by cytotoxicity assay on Vero cells (50% cytotoxic dose). When two prophages were inserted in the host chromosome, Shiga toxin production and the rate of lytic cycle activation fell. The cI repressor seems to be involved in incorporation of the second prophage. Incorporation and establishment of the lysogenic state of the two prophages, which lowers toxin production, could be regulated by the CI repressors of both prophages operating in trans. Although the sequences of the cI genes of the phages studied differed, the CI protein conformation was conserved. Results indicate that the presence of more than one prophage in the host chromosome could be regarded as a mechanism to allow genetic retention in the cell, by reducing the activation of lytic cycle and hence the pathogenicity of the strains.

scholarly journals Accessory DNA in the Genomes of Representatives of the Escherichia coli Reference Collection

1999 ◽  
Vol 181 (8) ◽  
pp. 2548-2554 ◽  
Author(s):  
Ana Hurtado ◽  
Francisco Rodríguez-Valera
Keyword(s):  
Escherichia Coli ◽  
Rapd Markers ◽  
Random Amplified Polymorphic Dna ◽  
The Other ◽  
Rna Helicases ◽  
Significant Similarity ◽  
E Coli ◽  
Reference Collection ◽  
Different Strains ◽  
K 12

ABSTRACT Different strains of the Escherichia coli reference collection (ECOR) differ widely in chromosomal size. To analyze the nature of the differential gene pool carried by different strains, we have followed an approach in which random amplified polymorphic DNA (RAPD) was used to generate several PCR fragments. Those present in some but not all the strains were screened by hybridization to assess their distribution throughout the ECOR collection. Thirteen fragments with various degrees of occurrence were sequenced. Three of them corresponded to RAPD markers of widespread distribution. Of these, two were housekeeping genes shown by hybridization to be present in all theE. coli strains and in Salmonella enterica LT2; the third fragment contained a paralogous copy of dnaK with widespread, but not global, distribution. The other 10 RAPD markers were found in only a few strains. However, hybridization results demonstrated that four of them were actually present in a large selection of the ECOR collection (between 42 and 97% of the strains); three of these fragments contained open reading frames associated with phages or plasmids known in E. coli K-12. The remaining six fragments were present in only between one and four strains; of these, four fragments showed no similarity to any sequence in the databases, and the other two had low but significant similarity to a protein involved in the Klebsiella capsule synthesis and to RNA helicases of archaeal genomes, respectively. Their percent GC, dinucleotide content, and codon adaptation index suggested an exogenous origin by horizontal transfer. These results can be interpreted as reflecting the presence of a large pool of strain-specific genes, whose origin could be outside the species boundaries.

scholarly journals Structural genes for nitrate-inducible formate dehydrogenase in Escherichia coli K-12.

Genetics ◽  
1990 ◽  
Vol 125 (4) ◽  
pp. 691-702 ◽  
Author(s):  
B L Berg ◽  
V Stewart
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Formate Dehydrogenase ◽  
Recombinant Dna ◽  
Structural Genes ◽  
Respiratory Pathway ◽  
E Coli ◽  
Formate Oxidation ◽  
Operon Expression ◽  
K 12

Abstract Formate oxidation coupled to nitrate reduction constitutes a major anaerobic respiratory pathway in Escherichia coli. This respiratory chain consists of formate dehydrogenase-N, quinone, and nitrate reductase. We have isolated a recombinant DNA clone that likely contains the structural genes, fdnGHI, for the three subunits of formate dehydrogenase-N. The fdnGHI clone produced proteins of 110, 32 and 20 kDa which correspond to the subunit sizes of purified formate dehydrogenase-N. Our analysis indicates that fdnGHI is organized as an operon. We mapped the fdn operon to 32 min on the E. coli genetic map, close to the genes for cryptic nitrate reductase (encoded by the narZ operon). Expression of phi(fdnG-lacZ) operon fusions was induced by anaerobiosis and nitrate. This induction required fnr+ and narL+, two regulatory genes whose products are also required for the anaerobic, nitrate-inducible activation of the nitrate reductase structural gene operon, narGHJI. We conclude that regulation of fdnGHI and narGHJI expression is mediated through common pathways.

Polyester Cloth–Based Hybridization Array System for Identification of Enterohemorrhagic Escherichia coli Serogroups O26, O45, O103, O111, O121, O145, and O157

2012 ◽  
Vol 75 (9) ◽  
pp. 1691-1697 ◽  
Author(s):  
BURTON W. BLAIS ◽  
MARTINE GAUTHIER ◽  
MYLÈNE DESCHÊNES ◽  
GEORGE HUSZCZYNSKI
Keyword(s):  
Escherichia Coli ◽  
Marker Gene ◽  
Enterohemorrhagic Escherichia Coli ◽  
Oligonucleotide Probes ◽  
E Coli ◽  
Polyester Cloth ◽  
Gene Profiles ◽  
Pcr Products ◽  
Different Strains ◽  
Immunoenzymatic Assay

A cloth-based hybridization array system (CHAS) was developed for the identification of foodborne colony isolates of seven priority enterohemorrhagic Escherichia coli (EHEC-7) serogroups targeted by U.S. food inspection programs. Gene sequences associated with intimin; Shiga-like toxins 1 and 2; and the antigenic markers O26, O45, O103, O111, O121, O145, and O157 were amplified in a multiplex PCR incorporating a digoxigenin label, and detected by hybridization of the PCR products with an array of specific oligonucleotide probes immobilized on a polyester cloth support, with subsequent immunoenzymatic assay of the captured amplicons. The EHEC-7 CHAS exhibited 100% inclusivity and 100% exclusivity characteristics with respect to detection of the various markers among 89 different E. coli strains, with various marker gene profiles and 15 different strains of non–E. coli bacteria.

Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli

1982 ◽  
Vol 152 (1) ◽  
pp. 81-88
Author(s):  
E H Berglin ◽  
M B Edlund ◽  
G K Nyberg ◽  
J Carlsson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Chelating Agent ◽  
Fold Increase ◽  
Bactericidal Effect ◽  
Anaerobic Conditions ◽  
Dna Breakage ◽  
E Coli ◽  
K 12

Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

scholarly journals pH-Dependent Catabolic Protein Expression during Anaerobic Growth of Escherichia coli K-12

2004 ◽  
Vol 186 (1) ◽  
pp. 192-199 ◽  
Author(s):  
Elizabeth Yohannes ◽  
D. Michael Barnhart ◽  
Joan L. Slonczewski
Keyword(s):  
Escherichia Coli ◽  
Ph Regulation ◽  
Metabolic Enzymes ◽  
Anaerobic Growth ◽  
High Ph ◽  
E Coli ◽  
Catabolic Enzymes ◽  
Periplasmic Proteins ◽  
Ph Dependent ◽  
K 12

ABSTRACT During aerobic growth of Escherichia coli, expression of catabolic enzymes and envelope and periplasmic proteins is regulated by pH. Additional modes of pH regulation were revealed under anaerobiosis. E. coli K-12 strain W3110 was cultured anaerobically in broth medium buffered at pH 5.5 or 8.5 for protein identification on proteomic two-dimensional gels. A total of 32 proteins from anaerobic cultures show pH-dependent expression, and only four of these proteins (DsbA, TnaA, GatY, and HdeA) showed pH regulation in aerated cultures. The levels of 19 proteins were elevated at the high pH; these proteins included metabolic enzymes (DhaKLM, GapA, TnaA, HisC, and HisD), periplasmic proteins (ProX, OppA, DegQ, MalB, and MglB), and stress proteins (DsbA, Tig, and UspA). High-pH induction of the glycolytic enzymes DhaKLM and GapA suggested that there was increased fermentation to acids, which helped neutralize alkalinity. Reporter lac fusion constructs showed base induction of sdaA encoding serine deaminase under anaerobiosis; in addition, the glutamate decarboxylase genes gadA and gadB were induced at the high pH anaerobically but not with aeration. This result is consistent with the hypothesis that there is a connection between the gad system and GabT metabolism of 4-aminobutanoate. On the other hand, 13 other proteins were induced by acid; these proteins included metabolic enzymes (GatY and AckA), periplasmic proteins (TolC, HdeA, and OmpA), and redox enzymes (GuaB, HmpA, and Lpd). The acid induction of NikA (nickel transporter) is of interest because E. coli requires nickel for anaerobic fermentation. The position of the NikA spot coincided with the position of a small unidentified spot whose induction in aerobic cultures was reported previously; thus, NikA appeared to be induced slightly by acid during aeration but showed stronger induction under anaerobic conditions. Overall, anaerobic growth revealed several more pH-regulated proteins; in particular, anaerobiosis enabled induction of several additional catabolic enzymes and sugar transporters at the high pH, at which production of fermentation acids may be advantageous for the cell.

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