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Microbial Biotechnology Sep 2022A system consisting of a connected mixed and tubular bioreactor was designed to study bacterial biofilm formation and the effect of its exposure to bacteriophages under...
A system consisting of a connected mixed and tubular bioreactor was designed to study bacterial biofilm formation and the effect of its exposure to bacteriophages under different experimental conditions. The bacterial biofilm inside silicone tubular bioreactor was formed during the continuous pumping of bacterial cells at a constant physiological state for 2 h and subsequent washing with a buffer for 24 h. Monitoring bacterial and bacteriophage concentration along the tubular bioreactor was performed via a piercing method. The presence of biofilm and planktonic cells was demonstrated by combining the piercing method, measurement of planktonic cell concentration at the tubular bioreactor outlet, and optical microscopy. The planktonic cell formation rate was found to be 8.95 × 10 h and increased approximately four-fold (4×) after biofilm exposure to an LB medium. Exposure of bacterial biofilm to bacteriophages in the LB medium resulted in a rapid decrease of biofilm and planktonic cell concentration, to below the detection limit within < 2 h. When bacteriophages were supplied in the buffer, only a moderate decrease in the concentration of both bacterial cell types was observed. After biofilm washing with buffer to remove unadsorbed bacteriophages, its exposure to the LB medium (without bacteriophages) resulted in a rapid decrease in bacterial concentration: again below the detection limit in < 2 h.
Topics: Bacteria; Bacteriophage T4; Bacteriophages; Biofilms; Bioreactors; Escherichia coli; Plankton
PubMed: 35638465
DOI: 10.1111/1751-7915.14079 -
Viruses Apr 2019has been widely used in industry for fermentation purposes. However, it is also associated with the spoilage of foods and beverages, in particular, beer. There is an...
has been widely used in industry for fermentation purposes. However, it is also associated with the spoilage of foods and beverages, in particular, beer. There is an increasing demand for natural food preservation methods, and in this context, bacteriophages possess the potential to control such spoilage bacteria. Just a few studies on phages infecting have been performed to date and in the present study, we report the isolation and characterization of five virulent phages capable of infecting strains. The analysis reveals a high diversity among the isolates, with members belonging to both, the and families. One isolate, designated phage 3-521, possesses a genome of 140.8 kb, thus representing the largest phage genome sequenced to date. While the isolated phages do not propagate on beer-spoiling strains, phages showed activity against these strains, impairing the growth of some strains. The results highlight the potential of bacteriophage-based treatments as an effective approach to prevent bacterial spoilage of beer.
Topics: Bacteriophages; Beer; Fermentation; Food Microbiology; Genome, Viral; Genomics; Host Specificity; Levilactobacillus brevis; Phylogeny; Proteomics
PubMed: 31035495
DOI: 10.3390/v11050393 -
Molecular Biology and Evolution May 2021Bacteriophages (phages) evolve rapidly by acquiring genes from other phages. This results in mosaic genomes. Here, we identify numerous genetic transfers between...
Bacteriophages (phages) evolve rapidly by acquiring genes from other phages. This results in mosaic genomes. Here, we identify numerous genetic transfers between distantly related phages and aim at understanding their frequency, consequences, and the conditions favoring them. Gene flow tends to occur between phages that are enriched for recombinases, transposases, and nonhomologous end joining, suggesting that both homologous and illegitimate recombination contribute to gene flow. Phage family and host phyla are strong barriers to gene exchange, but phage lifestyle is not. Even if we observe four times more recent transfers between temperate phages than between other pairs, there is extensive gene flow between temperate and virulent phages, and between the latter. These predominantly involve virulent phages with large genomes previously classed as low gene flux, and lead to the preferential transfer of genes encoding functions involved in cell energetics, nucleotide metabolism, DNA packaging and injection, and virion assembly. Such exchanges may contribute to the observed twice larger genomes of virulent phages. We used genetic transfers, which occur upon coinfection of a host, to compare phage host range. We found that virulent phages have broader host ranges and can mediate genetic exchanges between narrow host range temperate phages infecting distant bacterial hosts, thus contributing to gene flow between virulent phages, as well as between temperate phages. This gene flow drastically expands the gene repertoires available for phage and bacterial evolution, including the transfer of functional innovations across taxa.
Topics: Bacteriophages; Biological Evolution; Gene Flow; Gene Transfer, Horizontal; Host-Pathogen Interactions; Recombination, Genetic
PubMed: 33570565
DOI: 10.1093/molbev/msab044 -
American Journal of Veterinary Research Aug 2011To isolate and characterize bacteriophages with strong in vitro lytic activity against various pathogenic Pseudomonas aeruginosa strains isolated from dogs with ocular...
OBJECTIVE
To isolate and characterize bacteriophages with strong in vitro lytic activity against various pathogenic Pseudomonas aeruginosa strains isolated from dogs with ocular infections.
SAMPLE
26 genetically distinct P aeruginosa isolates.
PROCEDURES
P aeruginosa strains were derived from dogs with naturally acquired ulcerative keratitis. From a large-scale screening for bacteriophages with potential therapeutic benefit against canine ocular infections, 2 bacteriophages (P2S2 and P5U5) were selected; host ranges were determined, and phage nucleic acid type and genetic profile were identified via enzymatic digestion. Electron microscopy was used to characterize bacteriophage ultrastructure. Bacteriophage temperature and pH stabilities were assessed by use of double-layer agar overlay titration. A cocultivation assay was used to evaluate the effect of the bacteriophages on bacterial host growth.
RESULTS
P5U5 was active against all P aeruginosa isolates, whereas P2S2 formed lytic plaques on plates of 21 (80.8%) isolates. For each bacteriophage, the genomic nucleic acid was DNA; each was genetically distinct. Ultrastructurally, P2S2 and P5U5 appeared likely to belong to the Podoviridae and Siphoviridae families, respectively. The bacteriophages were stable within a pH range of 4 to 12; however, titers of both bacteriophages decreased following heating for 10 to 50 minutes at 45° or 60°C. Growth of each P aeruginosa isolate was significantly inhibited in coculture with P2S2 or P5U5; the dose response was related to the plaque-forming unit-to-CFU ratios.
CONCLUSIONS AND CLINICAL RELEVANCE
Bacteriophages P2S2 and P5U5 appear to be good candidates for phage treatment of infection caused by pathogenic P aeruginosa in dogs.
Topics: Animals; Bacteriophage Typing; Bacteriophages; Corneal Ulcer; DNA, Viral; Dog Diseases; Dogs; Eye Infections; Genetic Variation; Host Specificity; Podoviridae; Pseudomonas Infections; Pseudomonas aeruginosa; Siphoviridae
PubMed: 21801066
DOI: 10.2460/ajvr.72.8.1079 -
Viruses Sep 2012Knowledge of phage-host interactions at a fundamental level is central to the design of rational strategies for the development of phage-resistant strains that may be... (Review)
Review
Knowledge of phage-host interactions at a fundamental level is central to the design of rational strategies for the development of phage-resistant strains that may be applied in industrial settings. Phages infecting lactic acid bacteria, in particular Lactococcus lactis and Streptococcus thermophilus, negatively impact on dairy fermentation processes with serious economic implications. In recent years a wealth of information on structural protein assembly and topology has become available relating to phages infecting Escherichia coli, Bacillus subtilis and Lactococcus lactis, which act as models for structural analyses of dairy phages. In this review, we explore the role of model tailed phages, such as T4 and SPP1, in advancing our knowledge regarding interactions between dairy phages and their hosts. Furthermore, the potential of currently investigated dairy phages to in turn serve as model systems for this particular group of phages is discussed.
Topics: Bacillus Phages; Bacteriophage T4; Bacteriophages; Dairying; Host-Pathogen Interactions; Industrial Microbiology; Lactococcus lactis; Models, Biological; Streptococcus thermophilus
PubMed: 23170165
DOI: 10.3390/v4091410 -
Current Microbiology Jul 2017The genomes of the type B3 bacteriophages that infect Caulobacter crescentus are among the largest phage genomes thus far deposited into GenBank with sizes over 200 kb....
The genomes of the type B3 bacteriophages that infect Caulobacter crescentus are among the largest phage genomes thus far deposited into GenBank with sizes over 200 kb. In this study, we introduce six new bacteriophage genomes which were obtained from phage collected from various water systems in the southeastern United States and from tropical locations across the globe. A comparative analysis of the 12 available genomes revealed a "core genome" which accounts for roughly 1/3 of these bacteriophage genomes and is predominately localized to the head, tail, and lysis gene regions. Despite being isolated from geographically distinct locations, the genomes of these bacteriophages are highly conserved in both genome sequence and gene order. We also identified the insertions, deletions, translocations, and horizontal gene transfer events which are responsible for the genomic diversity of this group of bacteriophages and demonstrated that these changes are not consistent with the idea that modular reassortment of genomes occurs in this group of bacteriophages.
Topics: Bacteriophages; Base Sequence; Caulobacter crescentus; Gene Order; Genome, Viral; Genomics
PubMed: 28393265
DOI: 10.1007/s00284-017-1248-4 -
Trends in Microbiology Apr 2010The discovery of an extraordinarily high level of mobile elements in the genome of Wolbachia, a widespread arthropod and nematode endosymbiont, suggests that this... (Review)
Review
The discovery of an extraordinarily high level of mobile elements in the genome of Wolbachia, a widespread arthropod and nematode endosymbiont, suggests that this bacterium could be an excellent model for assessing the evolution and function of mobile DNA in specialized bacteria. In this paper, we discuss how studies on the temperate bacteriophage WO of Wolbachia have revealed unexpected levels of genomic flux and are challenging previously held views about the clonality of obligate intracellular bacteria. We also discuss the roles this phage might play in the Wolbachia-arthropod symbiosis and infer how this research can be translated to combating human diseases vectored by arthropods. We expect that this temperate phage will be a preeminent model system to understand phage genetics, evolution and ecology in obligate intracellular bacteria. In this sense, phage WO might be likened to phage lambda of the endosymbiont world.
Topics: Animals; Arthropods; Bacteriophage lambda; Bacteriophages; Evolution, Molecular; Symbiosis; Wolbachia
PubMed: 20083406
DOI: 10.1016/j.tim.2009.12.011 -
Viruses Feb 2021For decades, bacteriophage purification has followed structured protocols focused on generating high concentrations of phage in manageable volumes. As research moves...
For decades, bacteriophage purification has followed structured protocols focused on generating high concentrations of phage in manageable volumes. As research moves toward understanding complex phage populations, purification needs have shifted to maximize the amount of phage while maintaining diversity and activity. The effects of standard phage purification procedures such as polyethylene glycol (PEG) precipitation and cesium chloride (CsCl) density gradients on both diversity and activity of a phage population are not known. We have examined the effects of PEG precipitation and CsCl density gradients on a number of known phage (M13, T4, and ΦX 174) of varying structure and size, individually and as mixed sample. Measurement of phage numbers and activity throughout the purification process was performed. We demonstrate that these methods, used routinely to generate "pure" phage samples, are in fact detrimental to retention of phage number and activity; even more so in mixed phage samples. As such, minimal amounts of processing are recommended to introduce less bias and maintain more of a phage population.
Topics: Bacteriophages; Cesium; Chlorides; Ultracentrifugation
PubMed: 33672780
DOI: 10.3390/v13020328 -
Journal of Virology May 2012Despite the fact that multidrug-resistant Klebsiella sp. strains emerge rapidly (Xu J, et al., Adv. Mater. Res. 268-270:1954-1956, 2011) and bacteriophages have been...
Despite the fact that multidrug-resistant Klebsiella sp. strains emerge rapidly (Xu J, et al., Adv. Mater. Res. 268-270:1954-1956, 2011) and bacteriophages have been reported to be useful in controlling these bacteria (Kumari S, Harjai K, Chhibber S, J. Med. Microbiol. 60:205-210, 2011), the complete genome sequences of only five Klebsiella phages (four siphoviruses and one myovirus) can be found in databases. In this paper, we report on the complete genome sequence of Klebsiella sp.-infecting bacteriophage vB_KleM_RaK2. With a genome size of 345,809 bp, this is the second largest myovirus and the largest Klebsiella phage sequenced to date. This phage differs substantially from other myoviruses since 411 out of 534 vB_KleM_RaK2 open reading frames have no known functions and lack any reliable database matches. Comparative analysis of the genome sequence of vB_KleM_RaK2 suggests that this phage forms a distinct phylogenetic branch within the family Myoviridae of tailed bacteriophages.
Topics: Bacteriophages; Genome, Viral; Klebsiella; Molecular Sequence Annotation; Molecular Sequence Data; Phylogeny
PubMed: 22492928
DOI: 10.1128/JVI.00347-12 -
Virology Dec 2019Bacteriophages are abundant in the environment, yet the vast majority have not been discovered or described. Many characterized bacteriophages infect a small subset of...
Bacteriophages are abundant in the environment, yet the vast majority have not been discovered or described. Many characterized bacteriophages infect a small subset of Enterobacteriaceae hosts. Despite its similarity to Escherichia coli, the pathogenic Shigella flexneri has relatively few known phages, which exhibit significant differences from many E. coli phages. This suggests that isolating additional Shigella phages is necessary to further explore these differences. To address questions of novelty and prevalence, high school students isolated bacteriophages on non-pathogenic strains of enteric bacteria. Results indicate that Shigella phages are abundant in the environment and continue to differ significantly from E. coli phages. Our findings suggest that Shigella-infecting members of the Ounavirinae subfamily continue to be over-represented and show surprisingly low diversity within and between sampling sites. Additionally, a podophage with distinct genomic and structural properties suggests that continued isolation on non-model species of bacteria is necessary to truly understand bacteriophage diversity.
Topics: Adolescent; Bacteriophages; Female; Fresh Water; Genome, Viral; Humans; Male; Myoviridae; Phylogeny; Shigella flexneri; Soil Microbiology; Viral Proteins
PubMed: 31569014
DOI: 10.1016/j.virol.2019.09.007