How bacteria fight each other with the help of viral “mines”

(ORDO NEWS) — Viruses can infect not only human or animal cells, but also bacteria. These properties are possessed by a special type of virus called bacteriophages. In general, these viruses are not much different from any other, except that microbes are chosen as the host.

They also enter the cell in the same way, and multiply there. The bacteria themselves from a large number of viral particles eventually die, but not always. In some cases, the bacterium can live with the virus for a long time or even suppress it with the help of a protective mechanism.

There is also another scenario for the development of events – the DNA of the virus is integrated into the DNA of the bacterium, as, for example, HIV acts. In this case, the virus is in the form of a prophage for some time, and does not manifest itself in any way.

In fact, information about it exists, but the virus itself does not exist. We can say that he sleeps in the genome. For the virus to wake up, certain circumstances must occur. But what exactly? The mechanisms of “awakening” were not known to science. In a recent study, scientists at Harvard University concluded that other bacteria can wake up prophages.

How E. coli fights other bacteria

The authors of the work conducted experiments with colibactin species of Escherichia coli. The strains they used are known to secrete a dangerous substance called colibactin. It has the ability to damage the DNA in intestinal cells, causing them to mutate and form tumors, resulting in colon cancer.

But, the most interesting thing is that colibactin acts in a similar way not only on intestinal cells, but also on other bacteria. That is, E. coli can use this molecule to fight its competitors. Earlier we talked about how bacteria have complex relationships.

Some of them are able to get along with other species, while others prefer to develop only in the circle of their species, so they try to destroy competitors. It is for this reason that a kitchen sponge is an ideal habitat for bacteria – it has many isolated cells, as a result of which bacteria do not interfere with each other’s development.

How bacteria fight each other with the help of viral mines 2Some types of E. coli secrete colibactin, which makes changes to DNA

The fact that E. coli uses colibactin to fight other bacteria has long been known. However, scientists believed that this is a very ineffective weapon.

The fact is that this molecule is quite unstable, that is, it quickly collapses. Since it does not affect the cell for a long time, it does not have time to cause serious harm to it. Of course, it still causes some damage to DNA, but it is eliminated by DNA repair systems.

However, as researchers from Harvard University managed to find out, colibactin not only damages DNA, but also performs another function. Therefore, its effectiveness has been underestimated.

How do prophage viruses awaken in cells?

As the researchers write in an article published in the journal Nature, after damage to DNA by colibactin, the DNA repair process starts in bacteria. During this process, prophages awaken. That is, they turn into ordinary active viruses, as a result of which they destroy bacteria.

How bacteria fight each other with the help of viral mines 3 1Prophages are awakened by exposure to colibactin

As experts say, bacteria as a result of exposure to colibactin seem to be undermined by a viral mine. For this reason, over time, few other bacteria become near E. coli. True, this is provided that the competing bacteria were infected with viruses that are in the form of prophages.

True, such a mechanism of struggle may be unsafe for the colibactin bacteria themselves. The fact is that the number of viruses in the environment begins to increase, and as a result, there is a risk of infection for themselves.

A new technology for antibiotic therapy?

The discovery made by scientists could be of great importance in the fight against pathogenic bacteria. Many of them are known to be drug resistant. It is possible that colibactin in combination with bacteriophages will make it possible to destroy pathogens.

However, it is first necessary to study the molecular sequence of events. According to experts, this substance alone cannot wake up the virus. In addition to it, other molecules are involved, which are also secreted by colibactin bacteria.

In addition, colibactin, as mentioned above, can harm body cells and cause cancer. But most importantly, scientists have identified the very mechanism of fighting bacteria, and now they will be able to work further in this direction, and eventually find a way to safely use it for therapeutic purposes.


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