Bacteria share information to keep their communities stable

(ORDO NEWS) — Scientists have solved one of the mysteries of microbiology: how communities of microbes maintain their specialization despite changes in species composition.

It turned out that bacteria “teach beginners” the desired behavior by simply bombarding them with packages of genetic information.

Biologists from Duke University (USA) have proposed a simple explanation of how microbes form communities, where all of its members perform the same functions, regardless of the type of individual microorganisms.

It turned out that microbes, through horizontal gene transfer, constantly exchange instructions on what to do in the current environment. With such genetic pressure, communities literally reprogram their new members, thanks to which they can exist indefinitely.

Microbes live everywhere on Earth and usually they gather in communities (microbiomes) – large groups of microorganisms that live in a common environment, perform the same functions and have similar properties.

For example, the human gut microbiome includes several hundred species of bacteria, but they all do the same thing: they process food and destroy harmful bacteria that come with food.

For a long time, scientists could not understand exactly how microbiomes manage to maintain such a uniformity of functions and properties, if there can be hundreds of microbial species in a community.

American biologists have paid attention to the genes that encode this or that function. Their number in the microbiome gene pool remains surprisingly constant, even if one type of microbe in the community has abruptly changed to another.

Scientists have suggested that horizontal gene transfer is involved. This is the process of transferring genetic information between organisms of the same generation, and not from parents to offspring, as usually happens.

In this way, bacteria acquire new functions (for example, the ability to resist a new antibiotic) that are not in their innate genetic code. Figuratively speaking, microorganisms teach each other new skills.

Bacteria share information to keep their communities stable 2
The stability of genes in the microbiome directly depends on the frequency of their transfer between microbes

Scientists successfully tested their hypothesis using computer simulations, after which they conducted an experiment on real microbes. In their communities, there were up to 72 different types of bacteria that were constantly changing their genetic makeup – up to 13 genes at a time.

Observations have shown that the level of stability of certain genes is directly proportional to the frequency of exchange of these genes.

The most stable genes, which were just responsible for the main functions in a particular microbiome, literally flooded the living environment of bacteria. Packages of this genetic information were constantly circulating between microbes, leaving them no chance to “learn” some other functions.

The new study is interesting for more than just explaining how bacterial communities remain stable. Using horizontal gene transfer, it is possible to artificially create programmable microbiomes that will perform useful functions.

For example, clean water from dirt and toxic substances or turn waste into biofuel. According to Linchong Yu, a professor of biomedical engineering and one of the co-authors of the work, their approach allows you not to worry about the species composition of the microbiomes being constructed – the bacteria themselves will “force” their neighbors to do the right job.

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