Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Coliphages”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMedDate not supplied

[Interaction of topotecan, DNA topoisomerase I inhibitor, with double-stranded polydeoxyribonucleotides. III. Binding at the minor groove].

Interaction of topotecan (TPT) with calf thymus DNA, coliphage T4 DNA, and poly(dG-dC). poly(dG-dC) was studied by optical (linear flow dichroism, UV-vis spectroscopy) and quantum chemical methods. The linear dichroism (LD) signal of TPT bound to DNA was shown to have positive sign in the range 260-295 nm. This means that the plane of quinoline fragment (rings A and B) of TPT molecule form an angle lower 54 degrees with the long axis of DNA, and hence TPT molecule can not intercalate between DNA base pairs. TPT was established to bind to calf thymus DNA as readily as to coliphage T4 DNA whose all cytosines in the major groove were glycosylated at the 5th position. Consequently, the DNA major groove does not participate in TPT binding. TPT molecule was shown to compete with distamycin for binding sites in the minor groove of DNA and poly(dG-dC). poly(dG-dC). Thus, it was demonstrated for the first time that TPT binds to DNA at its minor groove.

Base Pairing↗
PubMed2003

Concentrations and inactivation of Ascaris eggs and pathogen indicator organisms in wastewater stabilization pond sludge.

During treatment in wastewater stabilization ponds (WSPs) many pathogens, in particular helminth eggs, are concentrated in the sludge layer. Because periodic removal of the sludge is often required, information is needed on the concentrations and inactivation of pathogens in the sludge layer to evaluate the public health risk they pose upon removal of the sludge. In this paper, previous reports on the sludge concentrations of various pathogen indicator organisms and helminth eggs are reviewed and results from our own recent experiments are reported. The advantages and disadvantages of several methods for studying inactivation in the sludge layer are discussed, as well as implications for the management of WSP sludge. In our recent experiments, which were conducted at three WSPs in central Mexico, sludge cores, dialysis chambers, and batch experiments were used to measure the inactivation rates of fecal coliform bacteria, fecal enterococci, F+ coliphage, somatic coliphage, and Ascaris eggs. The first-order inactivation rate constants were found to be approximately 0.1, 0.1, 0.01, 0.001, and 0.001 d(-1), respectively. The concentrations of all the organisms were found to vary both vertically and horizontally in the sludge layer; therefore, to determine the maximum and average concentration of organisms in the sludge layer of a WSP, complete sludge cores must be collected from representative locations throughout the pond.

Animals↗
PubMed2004

Bioaerosols from the land application of biosolids in the desert southwest USA.

This study evaluated bioaerosol emissions during land application of Class B biosolids in and around Tucson, Arizona, to aid in developing models of the fate and transport of bioaerosols generated from the land application of biosolids. Samples were collected for 20 min at distances between 2 m and 20 m downwind of point sources, using an SKC BioSampler impinger. A total of six samples were collected per sampling event, which consisted of a biosolid spray applicator applying liquid biosolids to a cotton field. Each application represented one exposure. Samples were collected in deionised water amended with peptone and antifoam agent. Ambient weather conditions were also monitored every 10 min following initiation of sampling. Concurrently with downwind samples, background (ambient) air samples were collected to compensate for any ambient airborne microorganisms. In addition, biosolids samples were collected for analysis of target indicator and pathogenic organisms. Soil samples were also collected and analysed. Significant numbers of heterotrophic plate count (HPC) bacteria were found in air samples collected during the biosolid application process. These could have arisen from soil particles being aerosolised during the land application process. Aerosolised soil may contribute significantly to the amount of aerosolised microorganisms. Soil particles may be able to more readily aerosolise, due to their low density, small particle size and low mass. Aerosolised HPC bacteria found during biosolids land application were similar to those found during normal tractor operation on non-biosolids applied fields. Coliforms and coliphages were not routinely detected even though they were found to be present in the biosolids at relatively high concentrations, 10(6) and 10(4)/g (dry weight) of biosolids respectively. This could be due to the die-off rate of aerosolised Gram-negative bacteria or sorption to the solid portion of the biosolids. Low numbers of aerosolised coliphages may likewise be due to sorption phenomena. We theorise that only organisms in the aqueous phase of the biosolids were available to desorb and be aerosolised. Animal viruses, which were not detected in the biosolids, were likewise not detected in the aerosol samples. Clostridium perfringens was detected in only a small percent of aerosol samples although it was detected during all weather conditions; other microorganisms were detected during more favourable environmental conditions (relative humidity >10%). Despite the fact that many of these organisms were present in the biosolids at significant concentrations, their presence in bioaerosols generated during the land application of biosolids was limited to only a small percentage of samples. Bacteria as well as viruses may sorb to biosolids, which contain a high percentage of organic matter, and desorption during land application of biosolids may not readily take place; therefore, these microorganisms may not be readily aerosolised.

Adsorption↗
PubMed2004

Inactivation of enteric microbes in water by electro-chemical oxidant from brine (NaCl) and free chlorine.

Oxidant solutions of mostly free chlorine can be electrochemically produced on-site from brine (NaCl) solution and used to disinfect water at the household or community level. In this study electrochemical oxidant (ECO) from brine and free chlorine were evaluated under laboratory conditions for inactivation of test microbes. Purified suspensions of Escherichia coli, the rugose strain of Vibrio cholerae, Clostridium perfringens spores, MS2 coliphage and Cryptosporidium parvum oocysts were treated with 2 mg/L or 5 mg/L solutions of ECO or free chlorine at 5 degrees C and 25 degrees C and pH 6, 8, and 10 (pH 7 and 25 degrees C only for C. parvum oocysts) for contact times <60 min. Under nearly all conditions, inactivation kinetics were more rapid for E. coli, V. cholerae, C. perfringens spores and MS2 coliphage with ECO than with free chlorine. ECO reduced E. coli, V. cholerae and MS2 by >4 log10 within 30 min and C. perfringens spores by >2 log10 within 10 min at pH 8 and 25 degrees C. Contrary to previous results, however, C. parvum oocysts were not inactivated by ECO, and the reasons for this difference are uncertain. The on-site electrolytic generation of oxidants from brine provided a convenient and inexpensive disinfectant containing free chlorine that was effective against many enteric microbes, for the treatment of household and community drinking-water supplies worldwide. However, the effectiveness of such oxidants for inactivating C. parvum oocysts was variable and sometimes ineffective.

Animals↗
PubMed2005

Seasonal virus removal by alternative onsite wastewater treatment systems.

Viral contamination of public waters is a leading health concern around the world, including in Minnesota where cold climate, abundant onsite systems on poor or thin soils, and abundant surface water resources present a significant risk of wastewater pathogens reaching sensitive water sources. Three alternative onsite treatment systems, a sand filter, peat filter and subsurface-flow constructed wetland (CW) at a field research site were evaluated for seasonal virus removal by seeding each with MS2 bacteriophage. The sand and peat filters and CW removed 2.7, 7.0, and 1.4 log10 of MS2, respectively, during summer and 1.8 and 6.9 log for the sand and peat filter during winter (CW not seeded). Somatic coliphage reductions for the sand filter, peat filter and CW were 2.9, 3.5, 1.0 log10 in summer, and 1.5, 2.8, 0.7 log10 during winter, respectively over a 3 year period. During this period, fecal coliform log10 reductions were 2.9, 4.6, 2.0 in summer for the sand and peat filters and CW, and 2.0, 4.6, 1.6 in winter. The peat filter was the most effective system for removing MS2, somatic coliphage and fecal coliforms during both winter and summer but all systems removed > 90% of viruses throughout the year.

Filtration↗
PubMedDate not supplied

[Problems of epidemic safety of drinking water use by the population of Russia].

Quantitative relationships were studied between the indicators (common coliform bacteria (CCP), glucose-positive bacteria (GPB), thermoduric bacteria (TDB), coliform bacteria, enterococci, clostridia, coliphages) and the opportunistic (Pseudomonas aeruginosa, Proteus, Klebsiella) and pathogenetic (Salmonella and intestinal viruses) microorganisms at the stages of effluent purification and decontamination, in processes of self-purification in the water reservoirs and of water preparation at water-supplying stations, as well as in the association with the incidence of acute intestinal infections of bacterial and viral genesis in different climatic zones of the country. Salmonella and the opportunistic bacteria of the Enterobacteriaceae family and Pseudomonas aeruginosa were found to be highly resistant to detoxifying agents and environmental factors, adaptable, able to reproduce in pure water, to long survive in underground waters, and to accumulate when water is desalinated at the erections. The cases of intestinal infections were found in the population using the portable water of the standard quality in terms of E. coli, TDB, CCB, and enterococci. In this case only the wider integral index of GPB, which includes the indices of E. coli, TDB, CCB, as well as lactose-negative pathogenic and opportunistic species retains its sanitary significance in terms of all signs and is a reliable indicator of the potential epidemic hazard of drinking water use. Long-term studies have provided evidence for the sanitary value of coliphages as indicators of viral drinking water contamination.

Disease Outbreaks↗
PubMedDate not supplied

[Expression of genes of prophage P1 Escherichia coli in cells of phytopathogenic Erwinia].

It is shown that the temperate coliphage P1Cmcts100 can transduce resistance to chloramphenicol in the cells of phytopathogenic bacteria Erwinia horticola and E. carotovora subsp. atroseptica. In the latter case the extrachromosomal DNA is inherited by recipient cells as the authentic prophage P1. The prophage P1 expresses rectification-modification EcoP1, as well as the genes of lysogenic conversion in phytopathogenic erwinia. Here the character of superinfection of transductants of E. atroseptica g125 by erwiniophage ZF40, by certain carotovoricines and coliphage T21 changes. Besides, the expression of genes of prophage P1 leads to the increase of survival of E. atroseptica when raising the environment temperature. Under these conditions the trans mutagenesis of bacterial chromosome can precede, that permits considering the phage P1 as a special tool for studying the molecular genetics of erwinia.

Anti-Bacterial Agents↗
PubMed2006

Application of microbial risk assessment on a residentially-operated bio-toilet.

The Sustainable Sanitation System is a new wastewater treatment system that incorporates a non-flushing toilet (Bio-toilet) that converts excreta into a reusable resource (as fertilizer or humus for organic agriculture) and reduces the pollution load to environments of the rivers, the lakes, and the sea. However, the risk of exposure to pathogens should be considered, because excrement is stored in the Bio-toilet. The aim of the present work is to analyze the health risk of dealing with the matrix (excreta and urine mixed with sawdust) of the Bio-toilet. Therefore, the fate of pathogenic viruses was investigated using coliphages as a virus index, and the modeling of the die-off rate in matrix was introduced. Then the microbial risk assessment was applied to a Bio-toilet that was actually used in a residential house; the infection risks of rotavirus and enterovirus as reference pathogens were calculated. According to the lab-scale experiment using coliphages for investing the die-off rate of viruses in the Bio-toilet, Qbeta had a higher die-off, which was greatly influenced by the water content and temperature. On the other hand, T4 showed a lower rate and was independent of water content. Therefore, these two phages' data were used as critical examples, such as viruses having high or low possibilities of remaining in the Bio-toilet during the risk assessment analysis. As the result of the risk assessment, the storage time required for an acceptable infectious risk level has wide variations in both rotavirus and enterovirus cases depending on the phage that was used. These were 0-260 days' and 0-160 days' difference, respectively.

Bacteriophage T4↗
PubMed1983

Specific antibodies and immunoglobulins in the oviductal fluid of the rhesus monkey.

Levels of specific antibodies against model antigens, immunoglobulins G and A and also albumin, in oviductal fluid were studied in the rhesus monkey during the periovulatory period. Animals were systemically or intravaginally immunized against T4 coliphages. Attempts to induce ovulation were made with human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG) monitored by radioimmunoassay of serum estrogen and progesterone. Collection of tubal fluid over 6 to 13 days was accomplished by surgical cannulation using a refrigerated extracorporeal collection device for each side. The results indicated the following: (1) The levels of specific antibodies against T4 coliphage and immunoglobulins (IgG, IgA) in the oviduct fluid averaged approximately one tenth of the serum values and showed a characteristic decrease and subsequent increase by a factor of 4 to 5 during and following treatment with hMG/hCG. The nadir was observed on the first or second day after hCG injection. (2) This pattern was similar in both ovulatory or nonovulatory cycles; therefore, these changes seem to be associated with the changes in serum estrogen levels. (3) There was a striking difference in serum and tubal fluid antibody levels after systemic versus after vaginal immunization by a factor of 10(3) and 10(4); however, the patterns in tubal fluid under treatment with hMG/hCG were very similar. (4) Specific antibodies in oviductal fluid and serum were mainly of the IgG class. (5) A concomitant change of total protein and albumin in oviduct fluid was also observed. The presence of sperm agglutination antibody in oviductal fluid was demonstrated in two monkeys after systemic immunization with homologous spermatozoa. The sperm antibody titers showed a similar pattern of change after hMG/hCG treatment.

Albumins↗
PubMed1963

FINE STRUCTURE OF THE BACTERIOPHAGE ATTACHMENT PROCESS.

Cota-Robles, E. H. (University of California, Riverside) and M. D. Coffman. Fine structure of the bacteriophage attachment process. J. Bacteriol. 86:266-273. 1963.-Electron microscopic examination of cells of Escherichia coli infected with coliphage T(2) suggested that the tail spikes of the virus attach to the cell wall. This is followed by a local disorganization of the cell wall and contraction of the virus tail resulting in the approximation of the virus to the cell. Ejection of the viral contents is followed by a retraction of the attached viral ghost from the infected cell. The bacterial cells reveal a fibrillar nuclear structure which in some cases surrounds material that appears to be of cytoplasmic origin.

Bacteriophages↗
PubMed1993

Structural analysis by energy dot plot of a large mRNA.

We have predicted the secondary structure of the entire 4217 nucleotide sequence of the genomic RNA of coliphage Q beta in one computer run using the computer program MFOLD that computes RNA structures within any prescribed increment of the computed minimum free energy. The results are presented in the form of an "energy dot plot" that shows both an optimal folding as well as the superposition of all base-pairs that can form in slightly suboptimal foldings. The plot reveals five large, well-determined, independent structural domains that cover approximately 50% of the viral genome. The predicted structural domains are consistent with and provide support for five large structural domains identified previously by quantitative electron microscopy in Q beta RNA. The dot plot also contains cluttered regions that indicate large numbers of alternative foldings within or between segments of an RNA molecule. These reflect the impossibility of accurate structure prediction and/or the biological reality of more than one folding. Weaker, long range structures, that are observed by electron microscopy in two alternate competing conformations, are located in the regions of the Q beta sequence that correspond to cluttered regions of the dot plot. The potential biological significance of these secondary structures is discussed.

Coliphages↗
PubMed2001

The protelomerase of the phage-plasmid N15 is responsible for its maintenance in linear form.

The prophage of coliphage N15 is not integrated into the bacterial chromosome but exists as a linear plasmid molecule with covalently closed ends. Upon infection of an Escherichia coli cell, the phage DNA circularises via cohesive ends. A phage-encoded enzyme, protelomerase, then cuts at another site, telRL, and forms hairpin ends (telomeres). We demonstrate that this enzyme acts in vivo on specific substrates, and show that it is necessary for replication of the linear prophage. We show that protelomerase is an end-resolving enzyme responsible for processing of replicative intermediates. Removal of protelomerase activity resulted in accumulation of replicative intermediates that were found to be circular head-to-head dimers. N15 protelomerase and its target site constitute a functional unit acting on other replicons independently of other phage genes; a mini-F or mini-P1 plasmid carrying this unit replicates as a linear plasmid with covalently closed ends. Our results suggest the following model of N15 prophage DNA replication. Replication is initiated at an internal ori site located close to the left end of plasmid DNA and proceeds bidirectionally. After replication of the left telomere, protelomerase cuts this sequence and forms two hairpin loops telL. After duplication of the right telomere (telR) the same enzyme resolves this sequence producing two linear plasmids. Alternatively, full replication of the linear prophage to form a circular head-to-head dimer may precede protelomerase-mediated formation of hairpin ends.

Base Sequence↗
PubMed2000

A functional lagging strand origin does not stabilize plasmid pMV158 inheritance in Escherichia coli.

Plasmid rolling circle replication generates single-stranded DNA intermediates. The intracellular amount of these molecules depends upon the efficiency of the conversion of single-stranded into double-stranded plasmid forms, that is, the functionality of the lagging strand origin (sso). The broad-host-range streptococcal plasmid pMV158 harbors two different ssos, both of which function efficiently in Streptococcus pneumoniae but poorly in Escherichia coli. Plasmid pMV158 is stably inherited in the pneumococcal host, but it is unstable in E. coli. A pMV158 derivative lacking its two ssos is unstable in both strains. We have cloned into this derivative the coliphage f1 lagging strand origin. Whereas the f1 sso was fully functional in E. coli, it did not show any activity in S. pneumoniae, a bacteria closely related to the pMV158 natural host. The presence of the f1 sso did not stabilize pMV158 inheritance in either the gram-positive or the gram-negative host.

Cloning, Molecular↗
PubMed1996

The Escherichia coli retrons Ec67 and Ec86 replace DNA between the cos site and a transcription terminator of a 186-related prophage.

Retrons are unusual, reverse transcriptase-encoding elements found in bacteria. Although there are a number of indications that retrons are mobile elements, their transposition has not been observed. The Escherichia coli retrons Ec67 and Ec86 are different retrons inserted at the same site and we have further characterized this site in search of clues to the mechanism of retron transposition. We confirm, by extending previous sequence analysis, that Ec67 and Ec86 are inserted into prophages related to coliphage 186. Comparison with the recently published sequence of the 186 96-2% region indicates that the retrons have replaced approximately 180 bp of DNA between the phage cohesive end site (cos) and the transcription terminator of a phage DNA-packaging gene. These features--DNA replacement at the insertion site and the location of retron junctions near transcription terminators or DNA cleavage sites--are shared with other retrons and suggest ways in which retron transposition might have occurred.

Amino Acid Sequence↗
PubMed1975

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

Various Escherichia coli K12 Hfr donors transfer at low frequency portions of the E. coli genome to Proteus mirabilis. By remating such Proteus hybrids with the same or a different E. coli Hfr strain, other genetic characters could be added to yield diploid Proteus hybrids which contained more than 30 percent of the E. coli genome. The extent of the E. coli genetic material in these unstable Proteus diploid hybrids included segments with the following selected markers: gal, lac, ara, mel, mtl, and malA. Unselected markers known to map throughout this region of the chromosome were also detected in these hybrids. Among the markers expressed in Proteus hybrids with the E. coli malA region was the receptor site for coliphage lambda. Although plaques were not seen, lambda was adsorbed by the Proteus hybrids. Examination of DNA from the various Proteus hybrids by CsCl density gradient centrifugation showed a satellite component of E. coli DNA with a size that corresponded to the extent of the E. coli genome present as determined by genetic analysis.

Centrifugation, Density Gradient↗
PubMed1975

Evidence for a dual control of the initiation of host-cell lysis caused by phage lambda.

The timing of host-cell lysis by coliphage lambda is controlled by two separable systems. The lambdaS gene product acts as a positive effector of lysis while another protein, the lysis regulator, is an inhibitor of lysis. If the continuous function of the lysis regulator is interrupted in phage infected cells immediate lysis ensues. This lysis requires metabolic energy but not S gene activity. In contrast, S protein activity is stimulated by agents which uncouple and which block oxidative phosphorylation. The lysis regulator is thermolabile and several lines of evidence suggest that it may be the lambdarex gene product.

Bacteriolysis↗
PubMed1976

Isolation of lambda prophage mutants defective in structural genes: their use for the study of bacteriophage morphogenesis.

Mutants of coliphage lambda defective in structural genes were isolated and characterized. The isolation method consisted in lysogenizing bacteria with mutagenized phage and testing for inability to form plaques after heat induction. The mutants were propagated as prophages in the lysogens. Mutants in the region of the tail-genes U, V, G and H were enriched for by a selection method based on recombination and complementation with known mutants, and they were mapped by deletion mapping with newly isolated lambdadg's. The lysates of all the mutants were examined by electron microscopy. Some of the mutants showed phenotypes different from those of known amber mutants in the same genes. They are interpreted as producing partially active, altered gene products and might be useful for the studies of morphogenesis and of the mechanism of infection.

Coliphages↗