A team of researchers from different institutes of the Wellcome Genome Campus, in the United Kingdom, has managed to identify 70,000 hitherto unknown viruses in the human intestine, where they systematically infect the bacteria that live there. For now, it is unknown how they affect our bodies and the impact they have on our health. The finding has just been published in the journal ‘Cell’. The gut microbiome, that is, the extensive community of bacteria and other organisms that reside in our digestive system, plays a very important role in the digestion of food and in regulating the immune system, which is beneficial for us.

However, there is also no shortage of studies that link these microbial communities with conditions such as obesity, allergies, or liver disease. Surprisingly, the truth is that very little is still known about the microbiome. And although it includes a variety of microorganisms, including fungi, bacteria, and viruses, the vast majority of existing studies have only focused on bacteria, larger and easier to detect. In this new work, however, the researchers used a method called metagenomics, which analyzes all existing genetic material, to identify viruses as well. Later, they mapped all the individual genetic sequences found and compared them to existing databases to assign them to specific species. In total, the team analyzed more than 28,000 different gut microbiome samples, collected from 28 countries.

The process uncovered complete genomes of more than 140,000 species of viruses that live in the human gut, half of them unknown. Of course, each person does not carry all of those species, but only a fraction of them. The researchers also focused on ‘bacteriophage’ or ‘phage’ viruses, that is, capable of infecting bacteria. The reason for this, according to Luis Camarillo-Guerrero, lead author of the research, is that “we are still finding out what their role in human health is. It is probably correct to say that the vast majority of them are not harmful to us and that they are simply an integral component of our body’s microbiota. ” Bacteriophages, for example, could play a prominent role in the evolution of bacteria in our gut, providing them with advantageous genetic traits.

“Since bacterial communities are a critical component of our gut,” explains Camarillo-Guerrero, “it is not difficult to imagine that phages could be playing a key role in maintaining a healthy balance in it. However, there are known cases in which phages have also contributed to the development of diseases, from diphtheria, a serious bacterial infection, to botulism, which attacks the body’s nerves. Both diseases are, in effect, caused by toxins that are encoded in phage genes. The researchers, according to Camarillo-Guerrero, have published the genomes of these invading bacteria viruses in a new database called the ‘Gut Phage Database’, which from now on can be used for further studies. “A genome,” says the scientist, “is like the model of an organism. The amount of information that we can extract by knowing only the DNA sequence of an organism is very large