Isolation and characterization of bacteriophages specific for Rhizobium leguminosarum biovar phaseoli

1993 ◽  
Vol 39 (8) ◽  
pp. 775-779 ◽  
Author(s):  
B. Dhar ◽  
K. K. Upadhyay ◽  
R. M. Singh
Keyword(s):  
Latent Period ◽  
Rhizobium Leguminosarum ◽  
Osmotic Shock ◽  
Burst Size ◽  
Adsorption Rate ◽  
Lytic Cycle ◽  
Phage Titer ◽  
Isolation And Characterization ◽  
One Step ◽  
Step Growth

Two lytic phages, designated as H3V and R2V, specific for Rhizobium leguminosarum biovar phaseoli, were isolated and characterized. Phage H3V was active against four indigenous isolates (HURR-3, HURR-21, HURR-35, and HURR-56) and two standard strains (RCR-3605 and USDA-2669) whereas R2V was specific to one indigenous (Raj-2) and one standard (USDA-2676) strain; there was no cross infectivity. Both phages had distinct morphology; phage H3V had an oblate polyhedral head (58 × 76 nm) and a flexible noncontractile tail (120 × 10 nm), while phage R2V had a hexagonal head (56 nm wide) and a very short tail (11 × 10 nm). The lytic cycle of phage R2V requires Ca2+ ions (1 mM), which considerably reduce its latent period and burst size. Adsorption and one-step growth experiments of phages revealed that H3V had a slower adsorption rate (0.56 × 10−9 cm3/min), a longer latent period (255 min), and a higher burst size (240 plaque-forming units/cell) than R2V, which had an adsorption rate of 0.94 × 10−9 cm3/min, a 210-min latent period, and a burst size of 200 plaque-forming units/cell. Inactivation of these phages by heat, osmotic shock, and uv irradiation showed that phage H3V was comparatively more sensitive than R2V. These phages were frequently detected in healthy nodules of French beans (Phaseolus vulgaris) at two different field locations and no correlation between phage titer and nodule size or colour was observed. Phage titer varied from 2.8 × 102 to 1.2 × 106 plaque-forming units/nodule.Key words: Rhizobium, phages, morphology.

Isolation and characterization of two bacteriophages of a stem-nodulating Rhizobium strain from Sesbania rostrata

1984 ◽  
Vol 30 (5) ◽  
pp. 521-525 ◽  
Author(s):  
Philippe de Lajudie ◽  
Didier Bogusz
Keyword(s):  
Burst Size ◽  
Growth Cycle ◽  
Sesbania Rostrata ◽  
Isolation And Characterization ◽  
Rhizobium Strains ◽  
One Step ◽  
Average Burst Size ◽  
Step Growth ◽  
Phage Growth

Two rhizobiophages, RS1 and RS2, were isolated in Senegal from a soil sample and dry stem nodules of Sesbania rostrata, a tropical legume that is infected by two categories of Rhizobium strains: "stem strains," which nodulate both roots and stems (type strain, ORS571), and "root strains," which induce effective nodules only on roots. Both phages were found to have a host range restricted to ORS571; all root strains were found to be resistant. By electron microscopy, phage RS1 showed an hexagonal head 63 nm wide and a tail 87 nm long; phage RS2 revealed an hexagonal head 60 nm wide. Characterization of phage growth cycle by one-step growth experiments showed that the latent period was ca. 75 min for RS1 and ca. 4 h for RS2, that the rise period lasted ca. 2 h for both RS1 and RS2, and that the average burst size was ca. 100 for RS1 and 130 for RS2. Temperature denaturation occurred at 60–65 °C (RS1) and 45–50 °C (RS2). Serum neutralization tests revealed that the phages were not serologically related. In contrast to RS1, RS2 appeared to be temperate, since stable lysogens were isolated.

Isolation and characterization of a bacteriophage specific for Neisseria perflava

1976 ◽  
Vol 4 (1) ◽  
pp. 87-91
Author(s):  
V I Steinberg ◽  
E J Hart ◽  
J Handley ◽  
I D Goldberg
Keyword(s):  
Burst Size ◽  
Nucleic Acid Content ◽  
Single Strain ◽  
Isolation And Characterization ◽  
Double Stranded Dna ◽  
Antigenic Properties ◽  
One Step ◽  
Step Growth ◽  
High Degree ◽  
Neisseria Perflava

Six isolates from normal throat samples have been shown to contain phage active against Neisseria perflava. The phage isolates were similar in terms of host range, latent period, burst size, antigenic properties, morphology, and nucleic acid content. Neutralization studies with antisera demonstrated that the isolates exhibited a very high degree of serological relatedness. These results taken together suggested that the isolates represented a single strain of bacteriophage. This phage, which we have designated NP-1, exhibited a high degree of host specificity, attacking only one of the several strains of N. perflava tested and none of the other species tested. One-step growth experiments yielded minimum latent periods of approximately 35 min; average burst sizes varied from 34 to 63 plaque-forming units per cell. Electron micrographs revealed particles with heads averaging 75 nm in diameter and tails averaging 300 nm in length and 18 nm in diameter. The phage contained double-stranded DNA with a guanine plus cytosine content of 38%.

scholarly journals Aztreonam Lysine Increases the Activity of Phages E79 and phiKZ against Pseudomonas aeruginosa PA01

2021 ◽  
Vol 9 (1) ◽  
pp. 152
Author(s):  
Carly M. Davis ◽  
Jaclyn G. McCutcheon ◽  
Jonathan J. Dennis
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Morphological Changes ◽  
Burst Size ◽  
Type Iv Pili ◽  
Biofilm Growth ◽  
Promising Alternative ◽  
Type Iv ◽  
Alternative Treatment Option ◽  
One Step ◽  
Step Growth

Pseudomonas aeruginosa is a pernicious bacterial pathogen that is difficult to treat because of high levels of antibiotic resistance. A promising alternative treatment option for such bacteria is the application of bacteriophages; the correct combination of phages plus antibiotics can produce synergistic inhibitory effects. In this study, we describe morphological changes induced by sub-MIC levels of the antibiotic aztreonam lysine (AzLys) on P. aeruginosa PA01, which may in part explain the observed phage–antibiotic synergy (PAS). One-step growth curves for phage E79 showed increased adsorption rates, decreased infection latency, accelerated time to lysis and a minor reduction in burst size. Phage E79 plus AzLys PAS was also able to significantly reduce P. aeruginosa biofilm growth over 3-fold as compared to phage treatment alone. Sub-inhibitory AzLys-induced filamentation of P. aeruginosa cells resulted in loss of twitching motility and a reduction in swimming motility, likely due to a reduction in the number of polar Type IV pili and flagella, respectively, on the filamented cell surfaces. Phage phiKZ, which uses Type IV pili as a receptor, did not exhibit increased activity with AzLys at lower sub-inhibitory levels, but still produced phage–antibiotic synergistic killing with sub-inhibitory AzLys. A one-step growth curve indicates that phiKZ in the presence of AzLys also exhibits a decreased infection latency and moderately undergoes accelerated time to lysis. In contrast to prior PAS studies demonstrating that phages undergo delayed time to lysis with cell filamentation, these PAS results show that phages undergo accelerated time to lysis, which therefore suggests that PAS is dependent upon multiple factors, including the type of phages and antibiotics used, and the bacterial host being tested.

scholarly journals PHAGE FORMATION IN STAPHYLOCOCCUS MUSCAE CULTURES

1950 ◽  
Vol 34 (2) ◽  
pp. 231-250 ◽  
Author(s):  
Winston H. Price
Keyword(s):  
Aspartic Acid ◽  
Burst Size ◽  
Synthetic Medium ◽  
Growth Curves ◽  
Acid Synthesis ◽  
Virus Protein ◽  
Complete Medium ◽  
Multiplication Rate ◽  
One Step ◽  
Step Growth

1. Four strains of Staphylococcus muscae have been isolated which differ in their growth rates and phage syntheses in Fildes' synthetic medium. 2. Two of the strains when singly infected cannot release phage in Fildes' synthetic medium unless a substance present in certain acid-hydrolyzed proteins is added to the medium. One of these strains also requires other substance(s) present in acid-hydrolyzed proteins in order to grow in Fildes' medium. 3. The two strains which do not require the addition of the phage-stimulating factor have been found either to synthesize this substance, or one similar to it. One of these strains will not grow in Fildes' medium unless substance(s) present in acid-hydrolyzed proteins is added to the medium. 4. The purified acid-hydrolyzed protein factor necessary for virus liberation does not affect the multiplication rate of uninfected S. muscae cells in Fildes' synthetic medium. 5. The substance is not needed for the adsorption or the invasion of the host cell by the virus. In the absence of the factor, the virus is adsorbed to the cell and "kills" it. 6. An analysis carried out by means of the one-step growth curve technique has indicated that the substance is not concerned simply with the mechanism of virus release, but is necessary for some initial stage in virus synthesis. 7. With one bacterial strain not requiring the AHPF, aspartic acid had to be present at least during the minimum latent period for the cell to form virus. 8. In the absence of aspartic acid, the virus was adsorbed to the cell and killed it, but no virus was released from singly infected bacteria. 9. If the cells were grown in a medium containing aspartic acid and then resuspended in the medium minus aspartic acid, no virus was released, although such cells contained at least two times the amount of aspartic acid necessary for the burst size in the complete medium. 10. Aspartic acid, a constituent of the virus particle, appears from an analysis of one-step growth curves to take part in the initial phase of phage synthesis. 11. The effect of amino acids on virus formation is discussed in relation to the time sequence of virus protein and desoxyribonucleic acid synthesis.

scholarly journals Isolation and Characterization of a Single-Stranded RNA Virus Infecting the Marine Planktonic Diatom Chaetoceros tenuissimus Meunier

2008 ◽  
Vol 74 (13) ◽  
pp. 4022-4027 ◽  
Author(s):  
Yoko Shirai ◽  
Yuji Tomaru ◽  
Yoshitake Takao ◽  
Hidekazu Suzuki ◽  
Tamotsu Nagumo ◽  
...  
Keyword(s):  
Natural Waters ◽  
Rna Virus ◽  
Burst Size ◽  
Amino Acid Sequences ◽  
Lytic Cycle ◽  
Marine Diatom ◽  
Logarithmic Phase ◽  
Isolation And Characterization ◽  
Ssrna Virus ◽  
High Yields

ABSTRACT Diatoms are important components of the biological community and food web in the aquatic environment. Here, we report the characteristics of a single-stranded RNA (ssRNA) virus (CtenRNAV01) that infects the marine diatom Chaetoceros tenuissimus Meunier (Bacillariophyceae). The ca. 31-nm virus particle is icosahedral and lacks a tail. CtenRNAV01 forms crystalline arrays occupying most of the infected host's cytoplasm. By growth experiments, the lytic cycle and the burst size were estimated to be <24 h and ∼1 × 104 infectious units per host cell, respectively. Stationary-phase C. tenuissimus cultures were shown to be more sensitive to CtenRNAV01 than logarithmic-phase cultures. The most noticeable feature of this virus is its exceptionally high yields of ∼1010 infectious units ml−1; this is much higher than those of any other algal viruses previously characterized. CtenRNAV01 has two molecules of ssRNA of approximately 8.9 and 4.3 kb and three major proteins (33.5, 31.5, and 30.0 kDa). Sequencing of the total viral genome has produced only one large contig [9,431 bases excluding the poly(A) tail], suggesting considerable overlapping between the two RNA molecules. The monophyly of CtenRNAV01 compared to another diatom-infecting virus, Rhizosolenia setigera RNA virus, was strongly supported in a maximum likelihood phylogenetic tree constructed based on the concatenated amino acid sequences of the RNA-dependent RNA polymerase domains. Although further analysis is required to determine the detailed classification and nomenclature of this virus, these data strongly suggest the existence of a diatom-infecting ssRNA virus group in natural waters.

scholarly journals Isolation of a Novel Bacteriophage Specific for the Periodontal Pathogen Fusobacterium nucleatum

2010 ◽  
Vol 76 (21) ◽  
pp. 7243-7250 ◽  
Author(s):  
Pamela Machuca ◽  
Leslie Daille ◽  
Enrique Vinés ◽  
Liliana Berrocal ◽  
Mauricio Bittner
Keyword(s):  
Periodontal Disease ◽  
Burst Size ◽  
Fusobacterium Nucleatum ◽  
Amino Acid Identity ◽  
Periodontal Pathogen ◽  
Genetic Characteristics ◽  
Double Stranded Dna ◽  
Transmission Electron ◽  
One Step ◽  
Step Growth

ABSTRACT Fusobacterium nucleatum is a periodontal pathogen that has been directly associated with the development and progression of periodontal disease, a widespread pathology that affects the support tissues of the tooth. We isolated a new bacteriophage (FnpΦ02) that specifically infects this bacterium. Transmission electron microscopy showed that the virion is composed of an icosahedral head and a segmented tail. The size of the phage genome was estimated to be approximately 59 kbp of double-stranded DNA. The morphological features and the genetic characteristics suggest that FnpΦ02 is part of the Siphoviridae family. Using one-step growth and adsorption experiments, the latent period, burst size, and adsorption rate were estimated to be 15 h, 100 infectious units per cell, and 7.5 × 10−10 ml min−1, respectively. A small fragment of phage DNA was cloned and sequenced, showing 93% nucleotide identity with the phage PA6 of Propionibacterium acnes and amino acid identity with fragments of two proteins (Gp3 and Gp4) of this phage. To our knowledge, FnpΦ02 is the first phage described to infect Fusobacterium nucleatum and provides the base for future exploration of phages in the control of periodontal disease.

scholarly journals Characterization of Bacteriophage against Enterococcus faecium Resistant to Vancomycin Isolated from Chicken Skin

2019 ◽  
pp. 1-14
Author(s):  
Hazzierah Syaffieqah An Nadiah Azlan ◽  
Muhajir Hamid ◽  
Adelene Ai-Lian Song
Keyword(s):  
Latent Period ◽  
Growth Kinetics ◽  
Enterococcus Faecium ◽  
Burst Size ◽  
Single Step ◽  
Vancomycin Resistant Enterococcus ◽  
Chicken Skin ◽  
Step Growth ◽  
Vancomycin Resistant ◽  
Faecium Strain

Aims: To characterize bacteriophages with strong in vitro lytic activity against vancomycin resistant Enterococcus faecium before testing on the chicken skin for their efficacy. Study Design: An experimental was carried out to characterize two isolated bacteriophages against Enterococcus faecium and test for their efficacy on chicken skin. Study Place: The study was carried out in Laboratory of Vaccine and Immunotherapeutics, Institue of Bioscience, Universiti Putra Malaysia in Selangor, which is the most populous state in Malaysia. Methodology: Two host specific lytic phages against vancomycin resistant Enterococcus faecium strain FM8, designated as FM8-P1 and FM8-P2 were physiological characterized. This includes determination of their adsorption rate, multiplicity of infection, and single step growth kinetics. The optimum pH and temperature for both bacteriophages activity were also determined before tested on chicken skin at 4°C and 25°C, which represent chiller and room temperature in poultry production line. Results: Based on the result of single-step growth kinetics, the latent period of FM8-P1 was 35 min with a burst size of 460 particles per infected cells, while FM8-P2 has a shorter latent period (20 min) but a smaller burst size of 60 particles. The highest adsorption rate for FM8-P1 was 83% and FM8-P2 was 90% at 2 min and 4 min respectively. Both bacteriophages also exihibited a wide range of pH and temperature for their activity. Conclusion: The specificity, lytic activity and stability of FM8-P1 and FM8-P2 emphasized their potential in effectively eliminating the vancomycin resistant Enterococcus faecium strain FM8. However, further works are required to validate their in situ reliability.

scholarly journals Isolation and Characterization of a Novel Single-Stranded RNA Virus Infectious to a Marine Fungoid Protist, Schizochytrium sp. (Thraustochytriaceae, Labyrinthulea)

2005 ◽  
Vol 71 (8) ◽  
pp. 4516-4522 ◽  
Author(s):  
Yoshitake Takao ◽  
Keizo Nagasaki ◽  
Kazuyuki Mise ◽  
Tetsuro Okuno ◽  
Daiske Honda
Keyword(s):  
Single Molecule ◽  
Rna Virus ◽  
Burst Size ◽  
Genomic Analysis ◽  
Lytic Cycle ◽  
Host Cells ◽  
Membrane Structures ◽  
Isolation And Characterization ◽  
Ssrna Virus ◽  
Basic Characteristics

ABSTRACT Thraustochytrids are cosmopolitan osmoheterotrophic microorganisms that play important roles as decomposers, producers of polyunsaturated fatty acids, and pathogens of mollusks, especially in coastal ecosystems. SssRNAV, a novel single-stranded RNA (ssRNA) virus infecting the marine fungoid protist Schizochytrium sp. (Labyrinthulea, Thraustochytriaceae) was isolated from the coastal water of Kobe Harbor, Japan, in July 2000, and its basic characteristics were examined. The virus particle is icosahedral, lacks a tail, and is ca. 25 nm in diameter. SssRNAV formed crystalline arrays and random assemblies within the cytoplasm of host cells, and it was also concentrated along the intracellular membrane structures. By means of one-step growth experiments, the lytic cycle and the burst size were estimated to be <8 h and 5.8 × 103 to 6.4 × 104 infectious units per host cell, respectively. SssRNAV had a single molecule of ssRNA that was approximately 10.2 kb long, three major proteins (37, 34, and 32 kDa), and two minor proteins (80 and 18 kDa). Although SssRNAV was considered to have some similarities with invertebrate viruses belonging to the family Dicistroviridae based on its partial nucleotide sequence, further genomic analysis is required to determine the detailed classification and nomenclature of SssRNAV. Our results indicate that viral infection is one of the significant factors controlling the dynamics of thraustochytrids and provide new insights into understanding the ecology of these organisms.

scholarly journals CHARACTERIZATION OF T4 MUTANTS THAT PARTIALLY SUPPRESS THE INABILITY OF T4rII TO GROW IN LAMBDA LYSOGENS

Genetics ◽  
1976 ◽  
Vol 83 (3) ◽  
pp. 477-487
Author(s):  
Theodore Homyk ◽  
Angel Rodriguez ◽  
Jon Weil
Keyword(s):  
Burst Size ◽  
Personal Communication ◽  
Growth Cycle ◽  
Plaque Morphology ◽  
One Step ◽  
Step Growth ◽  
The One ◽  
Phage Growth ◽  
L1 And L2

ABSTRACT In the course of isolating viable T4 deletions that affect plaque morphology (Homyk and Weil 1974), two closely linked point mutants, sip1 and sip2, were obtained. They map between genes t and 52, cause a reduction in plaque size and burst size, and partially suppress the lethality of rII mutants for growth in lambda lysogens. These characteristics demonstrate that sip1 and sip2 are similar to mutants previously reported by Freedman and Brenner (1972). In addition, D. Hall (personal communication) has shown that sip1 and sip2 are similar to the mutant farP85, which affects the regulation of a number of early genes (Chace and Hall 1975).—Sip suppression of rII mutants can be demonstrated in one-step growth experiments, even when both rII genes are completely deleted. This indicates that sip mutants do not simply reduce the level of rII gene products required for growth in a lambda lysogen. Instead, they alter the growth cycle so as to partially circumvent the need for any rII products.—Mutations at two other sites, designated L1 and L2, reverse the poor phage growth caused by sip and, in the one case tested, reverse the rII-suppressing ability of sip.

scholarly journals Characterization of the Two-Component Abortive Phage Infection Mechanism AbiT from Lactococcus lactis

2002 ◽  
Vol 184 (22) ◽  
pp. 6325-6332 ◽  
Author(s):  
Julie D. Bouchard ◽  
Eric Dion ◽  
Frédéric Bissonnette ◽  
Sylvain Moineau
Keyword(s):  
Lactococcus Lactis ◽  
Burst Size ◽  
Lytic Cycle ◽  
Phage Infection ◽  
Site Directed Mutagenesis ◽  
Hydrophobic Region ◽  
Plasmid Copy ◽  
Isolation And Characterization ◽  
Fold Reduction

ABSTRACT During the production of fermented dairy products, virulent bacteriophages infecting Lactococcus lactis can delay or stop the milk acidification process. A solution to this biological problem consists of introducing natural phage barriers into the strains used by the dairy industry. One such hurdle is called abortive infection (Abi) and causes premature cell death with no or little phage progeny. Here, we describe the isolation and characterization of a novel Abi mechanism encoded by plasmid pED1 from L. lactis. The system is composed of two constitutively cotranscribed genes encoding putative proteins of 127 and 213 amino acids, named AbiTi and AbiTii, respectively. Site-directed mutagenesis indicated that a hydrophobic region at the C-terminal extremity of AbiTi is essential to the antiphage phenotype. The AbiT system is effective against phages of the 936 and P335 species (efficiency of plaquing between 10−5 and 10−7) and causes a 20-fold reduction in the efficiency to form centers of infection as well as a 10- to 12-fold reduction in the burst size. Its efficacy could be improved by raising the plasmid copy number, but changing the intrinsic ratio of AbiTi and AbiTii did not greatly affect the antiphage activity. The monitoring of the intracellular phage infection process by DNA replication, gene expression, and electron microscopy as well as the study of phage mutants by genome mapping indicated that AbiT is likely to act at a later stage of the phage lytic cycle.

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