Research groups from Instituto Gulbenkian de Ciência (IGC) that study evolution, immunity and microbiology unveiled two new mechanisms in the microbiota: in older populations, the bacterium E. coli evolves in a way that can become potentially pathogenic and increase the risk of disease and, according to data obtained in another study, the metabolism of the same bacterium present in the microbiota differs if it is alone or accompanied by other bacteria.

The discoveries are available in the latest edition of CURRENT BIOLOGY.

The research group led by Isabel Gordo looked at populations of young and old mice and how E. coli evolved in both communities. The surprising fact that resulted from this work shows that E. coli evolve in the older population so that it can become potentially pathogenic and increase the risk of disease. The inflammation associated with the older age of the organs gives an added stress factor to the bacterium causing it to evolve into a version more dangerous to the health of the host.

The research group led by Karina Xavier found that the metabolism of E. coli differs if it is alone or in the company of other bacteria. When introduced into the host alone, E. coli proved to be an excellent colonizer, gaining a lot of space in its environment and consuming amino acids. When it is introduced in the company of another bacteria from the microbiota, Blautia coccoides, the investigation revealed that the genetic changes of the bacterium happen in a faster way due to the interaction: there is competition for available nutrients and E. coli starts to consume other nutrients, only made available due to the presence of B. coccoides.

Driven by the discovery of mechanisms associated with the microbiota (the set of microbes that make up the intestinal flora) and its impact on health, the two scientific articles now published are the result of work previously developed at IGC and which involves three Research Groups. In 2014, when researchers first realized that the bacterium E. coli, when introduced into the host, developed genetic mutations with a speed and frequency never before anticipated, new questions arose: What is the influence of the other species of bacteria in the intestine in this process? What influence does host aging have on the process? What impact does inflammation have on the evolution of the microbiota? What genetic mutations occur and how do they happen?