June 25, 2022

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Exchangeable genome in bacteria is expected to resist killing of bacteriophages

Exchangeable genome in bacteria is expected to resist killing of bacteriophages



Exchangeable genome in bacteria is expected to resist killing of bacteriophages. 

Science: Deciphering the exchangeable genome in bacteria is expected to resist the killing of bacteriophages!

Introduction: Recently, research published in “Science” shows that researchers have studied how bacteria defend against bacterial viruses: bacteria have a set of mobile and exchangeable genomes, which are mainly used for one purpose: to defend against bacteriophages.

This allows the inherent defense mechanism of the genome to allow bacteria to switch their inherent innate immune function at an astonishing speed to fight bacteria and viruses.

How and how bacteria quickly develop resistance to viruses is critical to the development of phage-based anti-bacterial infection therapies.

Bacterial viruses, so-called bacteriophages, can destroy bacteria. Bacteria are often attacked by viruses. A research team led by Martin Polz, a microbiologist at the University of Vienna, has studied how bacteria defend against viral predators.

This study shows that bacteria have exchangeable genetic elements, which are specifically designed to resist viruses, which enables bacterial populations to switch their inherent innate immune functions at an alarming rate.

How and how bacteria quickly develop resistance to viruses is critical to the development of phage-based anti-bacterial infection therapies.

The research was published in the journal “Science” recently, and the researchers published an article entitled “Rapid evolutionary turnover of mobile genetic elements drives bacterial resistance to phages”.

Exchangeable genome in bacteria is expected to resist killing of bacteriophagesDOI: 10.1126/science.abb1083


Predatory interaction between bacteria and phages

Bacteriophages are viruses that use bacteria as host cells. In the process of self-reproduction, they destroy bacterial cells: infected bacteria produce viruses until they erupt.

As microbial predators, bacteriophages significantly shape various microbial communities, which play an important role in all environments, all living things, and human health. In addition, due to the increase in antibiotic resistance, bacteriophages are considered a promising alternative to antibiotics for the treatment of bacterial infections.

Martin Polz of the Center for Microbiology and Environmental Systems Science (CMESS) of the University of Vienna said: “People have actually used phages to fight bacteria a long time ago. However, they were subsequently replaced by antibiotics because the interaction between viruses and bacteria is still not Clear.”

About a year ago, the microbiologist moved from the Massachusetts Institute of Technology in Cambridge to the University of Vienna. A research project he initiated with his team at the Massachusetts Institute of Technology delves into this interaction.


International research team discovers rapid exchange of mobile defense genes

Research teams from the University of Vienna, the Massachusetts Institute of Technology and the Paris Sorbonne University in France have studied in detail how bacteria resist viruses.

The head of the research project explained: “Each bacterial cell has a set of defense genes that enable it to eliminate certain viruses. Our research shows that these defense genes are exchanged very quickly between bacterial cells.

This is possible because They are integrated into so-called mobile genetic elements (MGEs), which themselves control whether and when they are transferred from one cell to another.


The defense against viruses shaped the evolution of bacteria

Each bacterium not only has a core genome shared with all other bacteria of the same species, but also contains movable genetic elements. This mobile, exchangeable genome may differ between different bacteria, but its overall function is still poorly understood. Studies have shown that it is mainly used for one purpose: phage defense.

Therefore, the fight against viruses determines the exchange of genomes, which in turn determines the evolution of bacteria. Rotem Sorek, a professor at the Weizmann Institute of Science in Israel, commented on the results of the study: “This discovery highlights the importance of bacteriophage defense in the microbial world.”

Sorek was not involved in the study, but he was concerned about the interaction between bacteriophages and bacteria. Leading research has been conducted on the role. He said that through precise analysis of these defensive islands, scientists have solved a problem that has plagued researchers for the past decade.


Evolutionary Analysis of Marine Vibrio’s Natural Defense Mechanism

This study analyzed the defense mechanisms inherent in the genome. Fatima Aysha Hussain, the lead author of the study, explained: “Our results highlight that this innate immunity is mainly responsible for the defense against viruses.

According to laboratory experiments, it was previously assumed that bacteria mainly defend against viruses by modifying their surface receptors.” For three months, researchers have collected water samples on the New England coast every day to explore the interaction between Vibrio bacteria and viruses that interact with Vibrio in their actual habitat.

Through genomic and genetic analysis, they observed extremely rapid evolutionary changes: In the 93-day study, a single bacterium developed specific resistance through the exchange of movable genetic elements.

Lead researcher Martin Polz explained: “These changes occur within a few generations, that is, cell division. This means that bacteria can develop resistance to certain viruses in the wild for weeks to months.”


Design based on the importance of phage therapy

The interaction between bacteriophages and bacteria is very specific. Therefore, a virus attack can only be successful on a single bacterium, but not on the entire bacterial species.

Martin Polz said: “This study proves why this happens: defense genes are very diverse, and the exchange rate is very fast, so there are always a large number of drug-resistant individuals in the population.”

The findings of this study not only provide Basic knowledge of how the microbial community works. They also pointed out the challenge of using bacteriophages against bacteria: the rapid acquisition of drug resistance must be considered when developing phage therapies, precisely because movable genetic elements similar to our research are also responsible for the rapid development of antibiotic resistance.

Reference:

https://phys.org/news/2021-10-viruses-interchangeable-defense-genes.html

Exchangeable genome in bacteria is expected to resist killing of bacteriophages

(source:internet, reference only)


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