The human gut microbiome is home to trillions of different microbes, many of which are crucial to our health. For example, some microbes help us digest food, and produce bioactive compounds that can be beneficial to us. These healthy gut microbes can also help tamp down the growth of dangerous microbes that have been linked to various diseases. New research has shown that some groups of microbes that are associated with different diseases like colorectal cancer, type 2 diabetes, and colorectal cancer have been shaped by evolution, and are adapted to the human gut in very specific ways.
Some of these bacterial lineages are particularly adept at taking up residence in the human gut, and have been able to move into human populations around the world. The unique nature of some of these disease-associated microbes could also make them useful in diagnostic assays or therapeutic approaches that involved the gut microbiome. The findings have been reported in Nature.
Researchers that study the human gut microbiome have tended to group gut microbes based on their genomes. This study aimed to take another approach, and grouped gut microbes based on how they had adapted to the gut. The analysis still used genetic characteristics to find similar microbes, but in a way that took similar ecological changes into account.
In some cases, certain microbes had gained genetic mutations that enabled them to perform so well, they eliminated other species of microbes that were close relatives, but that did not carry that beneficial mutation. These ecological adaptations tend to create groups of similar microbes that are very distinct from others, and there are several species of gut bacteria that are like this.
"If you don't just count species but take evolutionary adaptation into account, you can identify the biologically relevant units in the microbiome much more accurately," explained first study author Xiaoqian Annie Yu of the Centre for Microbiology and Environmental Systems Science (CeMESS) at the University of Vienna. "Even within the same bacterial species, some populations occur more frequently than others in certain diseases. When all are considered together, this often remains hidden."
Some of these microbes have moved across continents, which is commonly associated with pathogens but seems to happen with other types of microbes as well.
"Our findings show that gut bacteria are also more dynamic than previously thought. Well-adapted strains can spread internationally and occupy new ecological niches," said senior study author Martin F. Polz, also of the University of Vienna.
This novel methodology might change the trajectory of gut microbiome research, and could improve the use of gut microbes in diagnostics and therapeutics.
Sources: University of Vienna, Nature
