Bacteria competition prevents villains from causing diseases – 12/18/2023 – Science

The diversity of microorganisms that exist within our species’ digestive system is crucial to prevent disease-causing microbes from multiplying in the intestine, indicate experiments conducted by European scientists.

Apparently, beneficial bacteria prevent the bad bacteria from causing health problems because they compete with them for nutrients. The results, if correct, could be an important step towards creating custom-made “microbial farms” in the digestive system, capable of protecting people from infections that are difficult to treat once they take hold in the body.

The research, which has just been published in the American specialized magazine Science, is the result of a collaboration between scientists from the University of Oxford, in the United Kingdom, and the University of Strasbourg, in France. Led by Kevin Foster and Olivier Cunrath, researchers conducted a series of tests to try to identify the best recipe for a balanced intestine, less vulnerable to pathogenic bacteria.

It has been known for a long time that the human intestine (and, of course, that of other animals) is inhabited by a huge diversity of microorganisms, as is the case with other parts of our body, such as the skin. In a sense, it is like a miniature forest or ocean, in which these species use the resources of the environment and cooperate or compete with each other.

The presence of such creatures is important, for example, for the absorption of certain nutrients from food that the human body is not able to capture with the same ease without this help. There is also evidence that the presence of certain microbial communities can influence obesity or metabolic dysfunctions.

And there was also data indicating the importance of the intestinal microbiota (group of microorganisms) for protection against disease-causing bacteria. The experiments by Foster, Cunrath and their colleagues attempted to investigate the roots of the process, first in vitro and then in mice whose microbiota were tightly controlled from birth.

The initial step in the process was to test beneficial bacteria one by one, comparing them with two problematic microbes: Salmonella enterica (which can cause gastroenteritis) and Klebsiella pneumoniaewhose presence increases the risk of antibiotic-resistant infections elsewhere in the body.

Initially, the researchers realized that the “good” microbes, when isolated, were not capable of preventing the multiplication of the virus. Salmonella and from Klebsiella. Next step: add more beneficial microorganisms to the cocktail — 5, 10 and up to 50 different species. It was then that things started to change.

The effect of controlling pathogenic (disease-causing) microbes was soon felt, and grew at the same rate as new “gut-friendly” bacteria were added to the mix. However, not all of them had the same beneficial effect: the combination of species had to contain at least the bacterial species Escherichia colialong with other microbes, so that it was possible to prevent the multiplication of pathogenic species.

The deeper reasons behind this began to become a little clearer when researchers examined in detail the regions of the DNA of these bacterial species responsible for producing proteins — basically the essential building blocks of cells.

What they found is that there is a large overlap between the basic protein production needs of the group of beneficial bacteria and those of harmful bacteria, most likely indicating that they need to consume a similar set of nutrients to survive.

In other words, it is as if the “good” bacteria devoured the villains’ dinner, leaving them with no way to continue multiplying, a hypothesis that was confirmed by other experiments. In theory, it would be possible to use this type of information to precisely produce a bacterial counterattack against a given infection.