INFLUENCE OF SELECTED HERBICIDES IN PHAGES OF SOME SOIL BACTERIA

1982 ◽  
Vol 62 (1) ◽  
pp. 217-220 ◽  
Author(s):  
E. B. ROSLYCKY
Keyword(s):  
Latent Period ◽  
Soil Bacteria ◽  
Rhizobium Meliloti ◽  
Burst Size ◽  
Lytic Activity ◽  
Agrobacterium Radiobacter ◽  
Host System ◽  
Average Burst Size ◽  
Homologous Antiserum ◽  
Particle Attachment

Various concentrations of paraquat, atrazine, simazine, linuron, diuron, and paraquat in combinations with each including simazine + diuron, and terbacil alone, did not inhibit lytic activity of four bacteriophages of Agrobacterium radiobacter, three bacteriophages of Rhizobium meliloti, three bacteriophages of R. trifolii, or two bacteriophages of Streptomyces chrysomallus. Generally, the herbicides had no effect on the neutralization of radiobacterphage PR-1001 with its homologous antiserum, the length of the latent period, the percent adsorption or the average burst size. In contrast, paraquat concentrations from 20 to 400 μg∙mL−1 gradually reduced the adsorption from 38 to 21% and the average burst size from 67 to 9 in the PR-1001:R-1001 phage: host system. The same concentrations, however, showed no effect on the particle attachment or the length of the latent period.

scholarly journals Isolation and Physiomorphological Characterization ofEscherichia coliO157:H7-Infecting Bacteriophages Recovered from Beef Cattle Operations

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Pushpinder Kaur Litt ◽  
Divya Jaroni
Keyword(s):  
Beef Cattle ◽  
Latent Period ◽  
Host Range ◽  
Cold Storage ◽  
Growth Parameters ◽  
Burst Size ◽  
Morphological Characteristics ◽  
Lytic Activity ◽  
E Coli ◽  
The Stability

Bacteriophages, recovered from beef cattle environment and specifically targetingEscherichia coliO157:H7, were examined for their physiological and morphological characteristics. Degree of bacterial lysis and host range of isolated bacteriophages was determined against 55 isolates ofE. coliO157:H7. Morphology of phages was examined under transmission electron microscope. Phage growth parameters, particularly rate of adsorption, rise period, latent period, and burst size were also determined. The stability of isolated phages was tested at acidic and alkaline pH, at high temperatures, and in cold storage. A total of 7 phages were isolated which showed lytic activity against 50 out of 55 isolates ofE. coliO157:H7. Based on the morphology, phages were classified into Myoviridae or Siphoviridae family. Phages had a rise period between 19 and 40 min, a short latent period between 12 and 30 min, and a large burst size (89–631 virions per infected cell), indicating high lytic activity. Phages remained stable for 24 h at a wide pH (1–11) and temperature range (40–60°C) and for 90 d in cold storage. Characterization of bacteriophages, with a diverse host range ofE. coliO157:H7, could aid in the development of effective biocontrol strategies for this pathogen in the food industry.

scholarly journals Host-Controlled Modification of Rhizobium Bacteriophage

1965 ◽  
Vol 18 (2) ◽  
pp. 333 ◽  
Author(s):  
EA Schwinghamer
Keyword(s):  
Host Specificity ◽  
Phenotypic Variation ◽  
Small Proportion ◽  
Burst Size ◽  
Specific Form ◽  
Host System ◽  
One Step ◽  
Average Burst Size ◽  
In Cells

Host-controlled phenotypic variation of host specificity was observed with two rhizobiophage strains, 0Ll and 0L5, following growth on six strains of Rhizobium legumino8arum and R. trifolii. The six hosts could be assigned to four groups, each group representing a different pattern of host specificity. Initial adaptation of 0L5 to hosts L2, L7, and L25 appeared to involve mutation, although replication in cells of these hosts generally involved additional phenotypic restriction. Restricted and unrestricted forms of a phage did not differ significantly in their ability to adsorb to several hosts. One-step analysis of the L25-specific form of 0L5 grown in L25 cells indicated a low average burst size of approximately one unrestricted plaque-forming unit in a small proportion of cells which were able to produce infective centres on L4. One-cycle analysis of L4-specific 0L5 modified by growth in L25 confirmed the phenotypic nature of phage variation in this phage-host system, and indicated that specificity for L4 was not replicated in L25.

Partial characterization of a new C3-type capsule-dissolving phage of Streptococcus cremoris

1979 ◽  
Vol 25 (10) ◽  
pp. 1182-1187 ◽  
Author(s):  
Maija-Liisa Saxelin ◽  
Eeva-Liisa Nurmiaho ◽  
M. P. Korhola ◽  
Veronica Sundman
Keyword(s):  
Latent Period ◽  
Burst Size ◽  
Buoyant Density ◽  
Partial Characterization ◽  
Milk Product ◽  
Streptococcus Cremoris ◽  
Sour Milk ◽  
Average Burst Size

A viscous, ropy, sour milk product, called 'viili,' is produced in Finland. Capsule-forming strains of Streptococcus cremoris are the typical starters for this product. Occasionally fermentation fails and results in a non-ropy clot. The reasons for these failures, however, are obscure. In one batch of spoiled 'viili,' a new C3-type bacteriophage, termed KSY1, was isolated. The head of the phage was about 230 nm long and about 50 nm wide and the tail was 35 nm long and carried a complex collar structure. Upon infection of a number of encapsulated cultures of S. cremoris with KSY1, the cocci, though not serving as a host of the phage, lost their capsules. A capsuleless strain, S. cremoris 249, served as a host. The latent period was about 150 min and the average burst size 80. The buoyant density of KSY1 was 1.436 g/cm3.

Identification and characterization of lytic bacteriophages specific to foodborne pathogenic Escherichia coli O157:H7

2020 ◽  
Vol 27 (1) ◽  
pp. 56-72
Author(s):  
Zeliha Yıldirim ◽  
Tuba Sakin ◽  
Mustafa Akçelik ◽  
Nefise Akçelik
Keyword(s):  
Escherichia Coli ◽  
Latent Period ◽  
Burst Size ◽  
Rapid Development ◽  
Protein Band ◽  
Lytic Activity ◽  
Host Cells ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Wide Ph Range

The objective of this study was to identify and characterize five different lytic bacteriophages specific to Escherichia coli O157:H7. vB_EcoM-P12, vB_EcoM-P13, vB_EcoM-P23, and vB_EcoM-P34 phages belonged to the Myoviridae family and vB_EcoS-P24 phage was in the Siphoviridae family. Their plaque sizes changed between 0.48 ± 0.03 and 0.90 ± 0.03 mm in diameter. stx1 and stx2 virulent gene regions were absent in the genome of five Eco-phages and their genome size was 33 kbp. The protein band profiles of the five phages were found to be different from each other. Their latent period, burst size, and burst time changed between 10–15 min, 72–144 PFU/cell and 20–35 min, respectively. Multiplicity of infection values and mutant frequency of the phages were among 0.1–0.001 and 1.14 × 10−7–3.69 × 10−8, respectively. The phages had strong lytic activity against their host bacteria ( E. coli NCTC 12900, ATCC 43888, and ATCC 35150) at 5–37 ℃ and adsorbed to their host cells by 92.7–97.5% in the first five minutes of incubation. These phages are thought to be good candidates as therapeutic and biocontrol agents against E. coli O157:H7 in the veterinary science and food industry due to short latent period, high burst size, rapid development in host cells, high lytic activity, high adsorption rate, stability over a wide pH range and high temperature, and absence of stx1 and stx2 genes.

scholarly journals THE GROWTH OF BACTERIOPHAGE

1939 ◽  
Vol 22 (3) ◽  
pp. 365-384 ◽  
Author(s):  
Emory L. Ellis ◽  
Max Delbrück
Keyword(s):  
Latent Period ◽  
Phage Particle ◽  
Burst Size ◽  
Plaque Formation ◽  
Late Time ◽  
Counting Method ◽  
Average Burst Size ◽  
The Individual ◽  
Escherichia Coli Phage ◽  
Bacterium Growth

1. An anti-Escherichia coli phage has been isolated and its behavior studied. 2. A plaque counting method for this phage is described, and shown to give a number of plaques which is proportional to the phage concentration. The number of plaques is shown to be independent of agar concentration, temperature of plate incubation, and concentration of the suspension of plating bacteria. 3. The efficiency of plating, i.e. the probability of plaque formation by a phage particle, depends somewhat on the culture of bacteria used for plating, and averages around 0.4. 4. Methods are described to avoid the inactivation of phage by substances in the fresh lysates. 5. The growth of phage can be divided into three periods: adsorption of the phage on the bacterium, growth upon or within the bacterium (latent period), and the release of the phage (burst). 6. The rate of adsorption of phage was found to be proportional to the concentration of phage and to the concentration of bacteria. The rate constant ka is 1.2 x 10–9 cm.8/min. at 15°C. and 1.9 x 10–9 cm.8/min. at 25°. 7. The average latent period varies with the temperature in the same way as the division period of the bacteria. 8. The latent period before a burst of individual infected bacteria varies under constant conditions between a minimal value and about twice this value. 9. The average latent period and the average burst size are neither increased nor decreased by a fourfold infection of the bacteria with phage. 10. The average burst size is independent of the temperature, and is about 60 phage particles per bacterium. 11. The individual bursts vary in size from a few particles to about 200. The same variability is found when the early bursts are measured separately, and when all the bursts are measured at a late time.

THE INFLUENCE OF SOIL AND ROOT EXTRACTS ON THE ASSOCIATIVE GROWTH OF SELECTED SOIL BACTERIA

1963 ◽  
Vol 9 (2) ◽  
pp. 187-197 ◽  
Author(s):  
E. C. S. Chan ◽  
H. Katznelson ◽  
J. W. Rouatt
Keyword(s):  
Mixed Culture ◽  
Soil Bacteria ◽  
Agar Medium ◽  
Soil Extract ◽  
Antagonistic Effect ◽  
Pseudomonas Sp ◽  
Population Changes ◽  
Agrobacterium Radiobacter ◽  
Root Extracts ◽  
Wheat Population

These studies are concerned with the growth interrelationships of mixed cultures of five soil organisms in soil extract and root extracts of 2-, 4-, and 8-week-old oats, soybeans, and wheat. Population changes of Agrobacterium radiobacter, Arthrobacter citreus, Azotobacter chroococcum, Bacillus cereus, and a Pseudomonas sp. in pure and mixed culture were followed by plating on selective media. B. cereus and A. chroococcum grew poorly alone or in mixed culture in the extracts. In soil extract, A. citreus predominated over, or was nearly equal in number to, the Gram-negative forms (Pseudomonas and Agrobacterium). In root extracts, Pseudomonas sp. always predominated over A. citreus in mixed culture. A. radiobacter was inhibited in mature root extracts (8-week-old plants) although in pure culture it recovered after a period. An antagonistic effect of Pseudomonas sp. on A. chroococcum plated on nitrogen-free agar medium was found to be related to the kind of agar used.

scholarly journals Biological and Genomic Characterization of a Novel Jumbo Bacteriophage, vB_VhaM_pir03 with Broad Host Lytic Activity against Vibrio harveyi

Pathogens ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1051
Author(s):  
Gerald N. Misol ◽  
Constantina Kokkari ◽  
Pantelis Katharios
Keyword(s):  
Phage Therapy ◽  
Vibrio Harveyi ◽  
Burst Size ◽  
Disease Outbreaks ◽  
Artemia Salina ◽  
Open Reading Frames ◽  
Lytic Activity ◽  
Economic Losses ◽  
Phylogenomic Analysis ◽  
Antibiotic Resistant

Vibrio harveyi is a Gram-negative marine bacterium that causes major disease outbreaks and economic losses in aquaculture. Phage therapy has been considered as a potential alternative to antibiotics however, candidate bacteriophages require comprehensive characterization for a safe and practical phage therapy. In this work, a lytic novel jumbo bacteriophage, vB_VhaM_pir03 belonging to the Myoviridae family was isolated and characterized against V. harveyi type strain DSM19623. It had broad host lytic activity against 31 antibiotic-resistant strains of V. harveyi, V. alginolyticus, V. campbellii and V. owensii. Adsorption time of vB_VhaM_pir03 was determined at 6 min while the latent-phase was at 40 min and burst-size at 75 pfu/mL. vB_VhaM_pir03 was able to lyse several host strains at multiplicity-of-infections (MOI) 0.1 to 10. The genome of vB_VhaM_pir03 consists of 286,284 base pairs with 334 predicted open reading frames (ORFs). No virulence, antibiotic resistance, integrase encoding genes and transducing potential were detected. Phylogenetic and phylogenomic analysis showed that vB_VhaM_pir03 is a novel bacteriophage displaying the highest similarity to another jumbo phage, vB_BONAISHI infecting Vibrio coralliilyticus. Experimental phage therapy trial using brine shrimp, Artemia salina infected with V. harveyi demonstrated that vB_VhaM_pir03 was able to significantly reduce mortality 24 h post infection when administered at MOI 0.1 which suggests that it can be an excellent candidate for phage therapy.

scholarly journals Lytic Exoenzymes of Soil Strains of Bacillus Representatives and Manifestations of their Biological Activity

2021 ◽  
Vol 83 (4) ◽  
pp. 54-62
Author(s):  
Yu.V. Korzh ◽  
◽  
I.V. Dragovoz ◽  
L.V. Avdeeva ◽  
◽  
...  
Keyword(s):  
Biological Activity ◽  
Soil Bacteria ◽  
Antagonistic Activity ◽  
Lytic Activity ◽  
Bacillus Sp ◽  
Genus Bacillus ◽  
Phytopathogenic Bacteria ◽  
Petri Dishes ◽  
Bacillus Strains ◽  
Test Cultures

Bacteria of the genus Bacillus make up a significant (8–12%) part of the soil microbiome. Manifestation of their biological activity, in particular, the antagonistic and lytic activity against other microorganisms directly depends on their exometabolites. According to the literature, such properties of soil bacteria of the genus Bacillus thus can be related to their various lytic exoenzymes. Aim. To evaluate the role of lytic exoenzymes of the studied soil bacteria strains of the genus Bacillus in the manifestation of their biological (antagonistic, lysing) activity. Methods. The antagonistic activity of bacteria strains of the genus Bacillus against phytopathogenic micromycetes was determined by the method of double culture in Petri dishes on potato-glucose agar. For qualitative analysis of the presence of extracellular enzymes, strains of bacteria of the genus Bacillus were plated on Petri dishes with solid mineral-salt medium and a suitable substrate inducer. The ratio of the diameter of substrate hydrolysis zone to the diameter of the colony was taken as the relative enzymatic activity of the culture. Bacteriolytic activity of the studied strains was determined by the change in optical density of living cells of phytopathogenic bacteria suspension at 540 nm. Results. Six strains of bacteria of the genus Bacillus were selected by the results of preliminary screening, with at least five types of lytic activity, namely proteolytic, chitinase, amylolytic, cellulase, and xylanase of different levels (low, average, high). Analysis of the antagonistic activity of the selected strains of bacteria of the genus Bacillus to the main groups of phytopathogenic bacteria (six test cultures) singled out the strain Bacillus sp. 41 for a careful study of the nature and spectrum of its antagonism. Analysis of the level of antagonistic activity of the selected Bacillus strains against the phytopathogenic micromycetes showed that the minimum decrease of antagonism (the decrease of growth inhibition zones) during the observation period (at the 3rd and 7th days) was in Bacillus sp. 41 strain. Therefore, only this strain showed a stable and relatively wide range of antagonistic activity against phytopathogens of bacterial and fungal etiology. The nature of this antagonism is probably complex and conditioned by the participation of various biochemical mechanisms, in particular, the synthesis of a complex of lytic exoenzymes. To assess the lysing activity of Bacillus strains, three strains with the highest proteolytic and cellulolytic activity of exoenzymes were taken from the six previously chosen. Only Bacillus sp.1913 strain showed high (70%) lytic activity against gram-negative polyphagous phytopathogen Pseudomonas syringae pv. syringae UCM B-1027T. Such activity of the strain did not manifest against the rest of the phytopathogenic test cultures. The high lytic activity of Bacillus sp. 1913 strain may be associated with high activity of exogenous proteases and cellulases of the lytic complex, which is quite consistent with the literature data on the lytic activity of bacteria of the genus Bacillus. Conclusions. The spectrum and activity of lytic exoenzymes of strains of the studied soil bacteria of the genus Bacillus indicate the indirect participation of these enzymes in the manifestation of biological activity (antagonistic and lytic).

The influence of radiomimetic substances on deoxyribonucleic acid synthesis and function studied in Escherichia coli / phage systems - III. Mutation of T 2 bacteriophage as a consequence of alkylation in vitro : the uniqueness of ethylation

1959 ◽  
Vol 150 (941) ◽  
pp. 497-508 ◽  
Keyword(s):  
Escherichia Coli ◽  
Burst Size ◽  
Alkylating Agents ◽  
Direct Consequence ◽  
Acid Synthesis ◽  
Deoxyribonucleic Acid Synthesis ◽  
Methane Sulphonate ◽  
Average Burst Size ◽  
And Function

Of a comprehensive set of alkylating agents tested, only two, namely, ethyl methane sulphonate and diethyl sulphate, have been found so to interact with T 2 bacteriophage that cells of Escherichia coli , infected with phage treated extracellularly, manifest a considerably increased likelihood of yielding mutated phage. Since this increase can occur where the infective titre of the phage and the latent period and average burst size of the infected bacteria remain unchanged, it is considered that the increased mutation rate is a direct consequence of the chemical treatment, although the alkylation itself does not constitute the mutation. A study of the manner of inactivation of the phage by these agents has not revealed any characteristic difference between ethylation and other alkylations which could be held to account for its apparent uniqueness.

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