Related Experiment Video
Updated: Jun 9, 2025
09:23
Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics
Published on: January 5, 2024
1.8K
Directed evolution of bacteriophages: thwarted by prolific prophage
Tracey Lee Peters1,2, Jacob Schow2, Emma Spencer2
1Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, USA.
Applied and Environmental Microbiology
|October 30, 2024
Summary
Prophages, not evolved phages, caused apparent host-range expansion in a directed evolution experiment. This highlights the need to screen for prophages in phage research, especially for therapeutic applications.
Area of Science:
- Microbiology
- Molecular Biology
- Evolutionary Biology
Background:
- Directed evolution is frequently used to expand bacteriophage host ranges, targeting resistant bacteria.
- This process involves iterative propagation of phages on bacterial hosts, theoretically yielding evolved phages.
- However, bacterial prophages can contaminate phage preparations, complicating experimental outcomes.
Purpose of the Study:
- To investigate host-range expansion observed during a directed evolution experiment using the Appelmans protocol.
- To identify the source of unexpected host-range expansion in the *Pseudomonas aeruginosa* phage-host system.
- To assess the impact of prophages on directed evolution experiments and phage therapy development.
Main Methods:
- Implementation of the Appelmans protocol for directed evolution of phages.
- Propagation of phage cocktails on multiple *Pseudomonas aeruginosa* strains.
- Sequencing of isolated phages and host strains to identify genetic components.
- Intraspecies antagonism assays to detect inhibitory activity and prophage presence.
Main Results:
- Observed rapid host-range expansion was attributed to a *Casadabanvirus* prophage, not evolved phages.
- The prophage originated from a lysogenic host included early in the experiment and infected multiple bacterial hosts.
- The prophage was present in half of the sequenced samples but showed no signs of evolution under experimental conditions.
- Intraspecies antagonism assays proved useful for detecting prophage presence.
Conclusions:
- Prophages can significantly impact directed evolution experiments, leading to erroneous conclusions about phage adaptation.
- Genetic verification of phages and screening for prophages are crucial, particularly for phage therapy applications.
- Intraspecies antagonism assays are valuable tools for baseline assessment and prophage detection in experimental design.
Related Concept Videos
01:16Viral Replication: Lysogenic Cycle
The lysogenic cycle is a crucial viral replication strategy that allows bacteriophages to persist within host cells without immediately destroying them. This process is primarily observed in temperate phages, such as bacteriophage lambda (λ), which infects Escherichia coli. The cycle allows the viral genome to persist across bacterial generations while keeping host cells viable.Integration of the Viral GenomeUpon infection, bacteriophage lambda attaches to the bacterial surface and injects...
00:43Lysogenic Cycle of Bacteriophages
61.9K
In contrast to the lytic cycle, phages infecting bacteria via the lysogenic cycle do not immediately kill their host cell. Instead, they combine their genome with the host genome, allowing the bacteria to replicate the phage DNA along with the bacterial genome. The incorporated copy of the phage genome is called the prophage. Some prophages can re-activate and enter the lytic cycle. This often occurs in response to a perturbation, such as DNA damage, but can also transpire in the absence of...
61.9K
01:30Lytic Cycle of Bacteriophages
70.4K
Bacteriophages, also known as phages, are specialized viruses that infect bacteria. A key characteristic of phages is their distinctive “head-tail” morphology. A phage begins the infection process (i.e., lytic cycle) by attaching to the outside of a bacterial cell. Attachment is accomplished via proteins in the phage tail that bind to specific receptor proteins on the outer surface of the bacterium. The tail injects the phage’s DNA genome into the bacterial cytoplasm. In the...
70.4K
01:20Viral Replication: Lytic Cycle
1
Bacteriophages, or phages, are viruses that specifically infect bacteria. Among them, T-even bacteriophages, such as T4, exhibit a well-characterized lytic replication cycle in Escherichia coli (E. coli). This process ensures the rapid proliferation of the virus while ultimately leading to the destruction of the bacterial host.Attachment and DNA InjectionThe infection process begins with the recognition and binding of the T4 phage to the E. coli cell surface. Tail fibers of the phage...
1
02:53CRISPR and crRNAs
16.8K
Bacteria and archaea are susceptible to viral infections just like eukaryotes; therefore, they have developed a unique adaptive immune system to protect themselves. Clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins (CRISPR-Cas) are present in more than 45% of known bacteria and 90% of known archaea.
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
16.8K
00:57Antibiotic Selection
52.4K
Overview
52.4K