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.

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.

Isolation and characterization of wetland VSW-3, a novel lytic cold-active bacteriophage of Pseudomonas fluorescens

2017 ◽  
Vol 63 (2) ◽  
pp. 110-118 ◽  
Author(s):  
Kunhao Qin ◽  
Xiuling Ji ◽  
Chunjing Zhang ◽  
Yafang Ding ◽  
Anxiu Kuang ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Burst Size ◽  
Isolation And Characterization ◽  
A Genome ◽  
Cold Active ◽  
Average Burst Size ◽  
20 Nm ◽  
High Degree ◽  
Thermal Stability Of

Wetlands are often called the “kidneys of the Earth” and contribute substantially to environmental improvement. Pseudomonas fluorescens is a major contaminant of milk products and causes the spoilage of refrigerated foods and fresh poultry. In this study, we isolated and characterized a lytic cold-active bacteriophage named VSW-3 together with P. fluorescens SW-3 cells from the Napahai wetland in China. Electron microscopy showed that VSW-3 had an icosahedral head (56 nm) and a tapering tail (20 nm × 12 nm) and a genome size of approximate 40 kb. On the basis of the top-scoring hits in the BLASTP analysis, VSW-3 showed a high degree of module similarity to the Pseudomonas phages Andromeda and Bf7. The latent and burst periods were 45 and 20 min, respectively, with an average burst size of 90 phage particles per infected cell. The pH and thermal stability of VSW-3 were also explored. The optimal pH was found to be 7.0 and the activity decreased rapidly when the temperature exceeded 60 °C. VSW-3 is a cold-active bacteriophage, hence, it is important to research its ability to prevent product contamination caused by P. fluorescens and to characterize its relationship with its host P. fluorescens in the future.

A BACTERIOPHAGE THAT ATTACKS NUMEROUS PHYTOPATHOGENIC XANTHOMONAS SPECIES

1958 ◽  
Vol 4 (5) ◽  
pp. 493-497 ◽  
Author(s):  
M. D. Sutton ◽  
H. Katznelson ◽  
C. Quadling
Keyword(s):  
Burst Size ◽  
Lytic Phage ◽  
Plant Materials ◽  
Single Burst ◽  
Xanthomonas Species ◽  
One Step ◽  
Average Burst Size ◽  
Step Growth ◽  
Rot Disease

This paper reports the isolation of a lytic phage that attacks in vitro numerous phytopathogenic Xanthomonas species, including X. campestris (Pammel) Dowson, the cause of black rot disease of crucifers. Although 'one-step' growth experiments suggested an average burst size of ca. four for this phage-host system, 'single burst' experiments indicated a burst size of ca. one hundred phage particles per bacterium. The particles have typical phage morphology, as determined by electron microscopy. This phage gave satisfactory results when used in the rapid plaque count test for detection of phage-sensitive bacteria in plant materials.

scholarly journals Isolation and Characterization of an Aeromonas punctata Bacteriophage

2015 ◽  
Vol 9 (1) ◽  
pp. 185-187 ◽  
Author(s):  
Cheng Kai ◽  
Zhang Denglan ◽  
Deng Jingxuan ◽  
Zhao Yijun
Keyword(s):  
Restriction Enzyme ◽  
Burst Size ◽  
Wuhan City ◽  
Isolation And Characterization ◽  
Double Stranded Dna ◽  
East Lake ◽  
Average Burst Size ◽  
Enzyme Pattern ◽  
Restriction Enzyme Pattern

AnAeromonas punctatabacteriophage, named as DH1, was isolated from East Lake, Wuhan city, China. Morphologically, phage DH1 showed a typicalMyoviridaestructure consisting of an isometric head (50 nm in diameter) and a visible tail. The bacteriophage had a latent period of about 90 minutes and an average burst size of about 125 PFU•Cell-1. Restriction enzyme pattern of the bacteriophage’s genome showed that the genome is a double-stranded DNA and about 34kb in size. The sequenced genomic fragments showed highly similarities to gp04 and gp16 sequence of otherMyoviridaebacteriophages at protein level.

scholarly journals Isolation and characterization Phage UPM1705 against multi-drug resistant K. pneumoniae 1705

2021 ◽  
pp. 19-25
Author(s):  
Omar Assafiri ◽  
Adelene Ai-Lian Song ◽  
Irwan Hanish ◽  
Geok Hun Tan ◽  
Khatijah Yusoff
Keyword(s):  
Burst Size ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Isolation And Characterization ◽  
Drug Resistant Bacteria ◽  
Transmission Electron ◽  
One Step ◽  
Almost All ◽  
Phage Growth ◽  
Bacteria Culture

The rise in in the number of drug-resistant bacteria that can resist almost all kinds of antibiotics is due to the overuse of these antibiotics (e.g., carbapenems). Thus, there is a need to find an alternative to antibiotic treatment such as the use of phages. In this study, phage UPM1705 was isolated from a polluted lake which can lyse its host Klebsiella pneumoniae ATCC BAA-1705. Based on morphological appearance from transmission electron microscopy, UPM1705 belongs to Caudovirales (Myoviridae). UPM1705 can reach a titer of 107 PFU/ml based on the double-layer method. It has a burst size of 298 PFU/bacteria cell and a latent period of 80 min, a rise period of 75 min, and adsorption time of 20 min based on a one-step growth curve assay using an MOI of 0.02. It was stable from 4°C to 80°C and retained its functionality at pH between 4 to 11, with pH of 7 being the optimum pH for the phage growth. The efficiency of UPM1705 was tested via a turbidity assay at MOI of 0.02, 0.2, and 2. UPM1705 was able to clear the turbidity of the host bacteria culture at all of these three MOIs. Thus, UPM1705 has the potential to be used for phage therapy.

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%.

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.

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.

Stepping-stones to One-step Growth: Frank Macfarlane Burnet's Role in Elucidating the Viral Nature of the Bacteriophages

2008 ◽  
Vol 19 (1) ◽  
pp. 83 ◽  
Author(s):  
Neeraja Sankaran
Keyword(s):  
Growth Pattern ◽  
Stepping Stones ◽  
Bacterial Origin ◽  
Considerable Debate ◽  
One Step ◽  
Viral Nature ◽  
Step Growth ◽  
The One ◽  
Phage Growth

The demonstration of the one-step growth pattern of the bacteriophages is generally regarded as the key evidence that bacteriophages were viruses rather than enzymes of bacterial origin, a matter of considerable debate among scientists since the bacteriophage was first described in 1917. While the credit for this demonstration is usually accorded to a 1939 paper on phage growth by Emory Ellis and Max Delbr�ck, closer scrutiny of phage research conducted in the intervening two decades reveals that these papers did not present a new idea, but rather extended and refined a line of investigation about the phages that had its conceptual antecedents in the earlier work. Of particular note is the work of the Australian, Frank Macfarlane Burnet, during the late 1920s and early 1930s. Burnet's work also furnished other important reasons besides one-step growth—derived from experiments on lysogeny—for favouring the virus theoryand discarding the enzyme theory of phage. This paper examines Burnet's contributions towards understanding of the nature of phage and makes the case that it was a tacit acceptance of the evidence and arguments that he presented that allowed Ellis and Delbr�ck to make assumptions about the bacteriophage, presented as fact in their papers.

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