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.

THE INDUCTION OF LAMBDA PROPHAGES BY CONTROLLED DESICCATION

1967 ◽  
Vol 13 (1) ◽  
pp. 33-43 ◽  
Author(s):  
S. J. Webb ◽  
M. D. Dumasia
Keyword(s):  
Escherichia Coli ◽  
Relative Humidity ◽  
Water Molecules ◽  
Compound I ◽  
Prophage Induction ◽  
E Coli ◽  
Escherichia Coli K12 ◽  
Number Of Cells

Cells of Escherichia coli K12 (λ +) and Escherichia coli M3 (λ59) were desiccated at various levels of relative humidity (R.H.). When the cells were cultured in an enriched medium and held at 55% R.H., induction of the prophage in 36% of E. coli K12 cells and 75% of E. coli M3 cells occurred. At 30% R.H. or 70% R.H., fewer inductions took place. The maximum number of cells in which prophage induction occurred was found 15 minutes after desiccation began with E. coli K12 and immediately after the cells were dried with E. coli M3. After the attainment of maximum levels of induction, plaque-forming ability was gradually destroyed, but the rate of destruction was dependent on the R.H. at which the cells were held. The plaque-forming ability of the free viruses and of cells in which prophage induction had occurred were destroyed by prolonged desiccation at different rates. Also, the loss of colony-forming ability of the cells was more rapid than the inactivation of plaque-forming ability of either induced prophages or the free viruses. The compound, i-inositol, prevented prophage induction by desiccation and also stopped the destruction of induced prophages within the cell.It is concluded that water molecules bound to the DNA hold the prophage to the host DNA and their removal results in induction.

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.

Modeling of Escherichia coli Inactivation by UV Irradiation at Different pH Values in Apple Cider

2004 ◽  
Vol 67 (6) ◽  
pp. 1153-1156 ◽  
Author(s):  
A. QUINTERO-RAMOS ◽  
J. J. CHUREY ◽  
P. HARTMAN ◽  
J. BARNARD ◽  
R. W. WOROBO
Keyword(s):  
Escherichia Coli ◽  
Uv Irradiation ◽  
Uv Light ◽  
Reduction Factor ◽  
Attractive Alternative ◽  
Bacterial Populations ◽  
Apple Cider ◽  
E Coli ◽  
Log Reduction ◽  
Uv Dose

This study examined the effects and interactions of UV light dose (1,800 to 20,331 μJ/cm2) and apple cider pH (2.99 to 4.41) on the inactivation of Escherichia coli ATCC 25922, a surrogate for E. coli O157:H7. A predictive model was developed to relate the log reduction factor of E. coli ATCC 25922 to the UV dose. Bacterial populations for treated and untreated samples were enumerated with the use of nonselective media. The results revealed that UV dose was highly significant in the inactivation of E. coli, whereas pH showed no significant effect at higher UV doses. Doses of 6,500 μJ/cm2 or more were sufficient to achieve a greater than 5-log reduction of E. coli. Experimental inactivation data were fitted adequately by a logistic regression model. UV irradiation is an attractive alternative to conventional methods for reducing bacteria in unpasteurized apple cider.

Involvement of the cgtA gene function in stimulation of DNA repair in Escherichia coli and Vibrio harveyi

Microbiology ◽  
2003 ◽  
Vol 149 (7) ◽  
pp. 1763-1770 ◽  
Author(s):  
Ryszard Zielke ◽  
Aleksandra Sikora ◽  
Rafał Dutkiewicz ◽  
Grzegorz Wegrzyn ◽  
Agata Czyż
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Dna Repair ◽  
Gene Product ◽  
Uv Irradiation ◽  
Vibrio Harveyi ◽  
Bacterial Species ◽  
Wild Type ◽  
E Coli ◽  
Stimulation Of

CgtA is a member of the Obg/Gtp1 subfamily of small GTP-binding proteins. CgtA homologues have been found in various prokaryotic and eukaryotic organisms, ranging from bacteria to humans. Nevertheless, despite the fact that cgtA is an essential gene in most bacterial species, its function in the regulation of cellular processes is largely unknown. Here it has been demonstrated that in two bacterial species, Escherichia coli and Vibrio harveyi, the cgtA gene product enhances survival of cells after UV irradiation. Expression of the cgtA gene was found to be enhanced after UV irradiation of both E. coli and V. harveyi. Moderate overexpression of cgtA resulted in higher UV resistance of E. coli wild-type and dnaQ strains, but not in uvrA, uvrB, umuC and recA mutant hosts. Overexpression of the E. coli recA gene in the V. harveyi cgtA mutant, which is very sensitive to UV light, restored the level of survival of UV-irradiated cells to the levels observed for wild-type bacteria. Moreover, the basal level of the RecA protein was lower in a temperature-sensitive cgtA mutant of E. coli than in the cgtA + strain, and contrary to wild-type bacteria, no significant increase in recA gene expression was observed after UV irradiation of this cgtA mutant. Finally, stimulation of uvrB gene transcription under these conditions was impaired in the V. harveyi cgtA mutant. All these results strongly suggest that the cgtA gene product is involved in DNA repair processes, most probably by stimulation of recA gene expression and resultant activation of RecA-dependent DNA repair pathways.

scholarly journals TolC-Dependent Exclusion of Porphyrins in Escherichia coli

2008 ◽  
Vol 190 (18) ◽  
pp. 6228-6233 ◽  
Author(s):  
Ryoko Tatsumi ◽  
Masaaki Wachi
Keyword(s):  
Escherichia Coli ◽  
Uv Irradiation ◽  
High Performance ◽  
Aminolevulinic Acid ◽  
Wild Type ◽  
E Coli ◽  
Chromatography Analysis ◽  
Increased Sensitivity ◽  
Mutant Cells ◽  
Reddish Brown Color

ABSTRACT We found that Escherichia coli tolC mutants showed increased sensitivity to 5-aminolevulinic acid (ALA), a precursor of porphyrins. The tolC mutant cells grown in the presence of ALA showed a reddish brown color under visible light and a strong red fluorescence under near-UV irradiation. Fluorescence spectrometry and high-performance liquid chromatography analysis showed that the tolC mutant cells grown in the presence of ALA accumulated a large amount of coproporphyrin(ogen) intracellularly. In contrast, the wild-type cells produced coproporphyrin extracellularly. The tolC mutant cells grown in the presence of ALA, which were capable of surviving in the dark, were killed by near-UV irradiation, suggesting that the intracellular coproporphyrin(ogen) renders these cells photosensitive. These results suggest that the TolC-dependent efflux system is involved in the exclusion of porphyrin(ogen)s in E. coli.

Effects of UV Irradiation on Selected Pathogens in Peptone Water and on Stainless Steel and Chicken Meat

2002 ◽  
Vol 65 (7) ◽  
pp. 1142-1145 ◽  
Author(s):  
T. KIM ◽  
J. L. SILVA ◽  
T. C. CHEN
Keyword(s):  
Escherichia Coli ◽  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Uv Irradiation ◽  
Processing Time ◽  
Chicken Meat ◽  
Escherichia Coli O157 ◽  
Uv Treatment ◽  
E Coli ◽  
Peptone Water

Effects of intensity and processing time of 254 nm UV irradiation on Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella Typhimurium were investigated. Intensities measured at 5.08, 10.1, 15.2, and 20.3 cm from the light source were 1,000, 500, 250, and 150 μW/cm2, respectively. Intensities of 250 or 500 μW/cm2 reduced all suspended pathogen cells in peptone water about 5 log cycles after 2 min and completely inactivated L. monocytogenes and E. coli O157:H7 after 3 min by reductions of 8.39 and 8.64 log cycles, respectively. Intensities of 250 or 500 μW/cm2 also reduced (P ≤ 0.05) the tested pathogens inoculated on stainless steel (SS) chips, and E. coli O157:H7 was completely destroyed at 500 μW/cm2 for 3 min. After UV treatment for 3 min at 500 μW/cm2, all selected pathogens on chicken meat with or without skin showed reduction ranges from 0.36 to 1.28 log cycles. Results demonstrated that UV irradiation could effectively decrease pathogens in peptone water and on SS but that it was less effective on chicken meat.

scholarly journals Enzymic synthesis of N-acetyl-l-phenylalanine in Escherichia coli K12

1971 ◽  
Vol 124 (5) ◽  
pp. 905-913 ◽  
Author(s):  
R. V. Krishna ◽  
P. R. Krishnaswamy ◽  
D. Rajagopal Rao
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Acetyl Coa ◽  
Ph Optimum ◽  
E Coli ◽  
Enzymic Synthesis ◽  
Escherichia Coli K12

1. Cell-free extracts of Escherichia coli K12 catalyse the synthesis of N-acetyl-l-phenylalanine from acetyl-CoA and l-phenylalanine. 2. The acetyl-CoA–l-phenylalanine α-N-acetyltransferase was purified 160-fold from cell-free extracts. 3. The enzyme has a pH optimum of 8 and catalyses the acetylation of l-phenylalanine. Other l-amino acids such as histidine and alanine are acetylated at slower rates. 4. A transacylase was also purified from E. coli extracts and its substrate specificity studied. 5. The properties of both these enzymes were compared with those of other known amino acid acetyltransferases and transacylases.

scholarly journals Functional Properties of Borrelia burgdorferi recA

2004 ◽  
Vol 186 (8) ◽  
pp. 2275-2280 ◽  
Author(s):  
Dionysios Liveris ◽  
Vishwaroop Mulay ◽  
Ira Schwartz
Keyword(s):  
Gene Expression ◽  
Borrelia Burgdorferi ◽  
Uv Irradiation ◽  
Reca Protein ◽  
Primary Role ◽  
Rapid Loss ◽  
E Coli ◽  
Uv Dose ◽  
Null Mutants

ABSTRACT Functions of the Borrelia burgdorferi RecA protein were investigated in Escherichia coli recA null mutants. Complementation with B. burgdorferi recA increased survival of E. coli recA mutants by 3 orders of magnitude at a UV dose of 2,000 μJ/cm2. The viability at this UV dose was about 10% that provided by the homologous recA gene. Expression of B. burgdorferi recA resulted in survival of E. coli at levels of mitomycin C that were lethal to noncomplemented hosts. B. burgdorferi RecA was as effective as E. coli RecA in mediating homologous recombination in E. coli. Furthermore, E. coli λ phage lysogens complemented with B. burgdorferi recA produced phage even in the absence of UV irradiation. The level of phage induction was 55-fold higher than the level in cells complemented with the homologous recA gene, suggesting that B. burgdorferi RecA may possess an enhanced coprotease activity. This study indicates that B. burgdorferi RecA mediates the same functions in E. coli as the homologous E. coli protein mediates. However, the rapid loss of viability and the absence of induction in recA expression after UV irradiation in B. burgdorferi suggest that recA is not involved in the repair of UV-induced damage in B. burgdorferi. The primary role of RecA in B. burgdorferi is likely to be a role in some aspect of recombination.

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