Our genes shape intestinal bacteria, according to new research

Our gut microbiome, the ever-changing “rainforest” of bacteria that live in our gut, is primarily affected by our lifestyle, including what we eat or the medications we take, according to most studies.

But a study from the University of Notre Dame has found at stake a much larger genetic component than was previously known.

In the study, recently published in Science, the researchers found that most bacteria in the gut microbiome are heritable after examining more than 16,000 profiles of gut microbiomes collected over 14 years from a long-studied baboon population in Kenya’s Amboseli National Park. However, this heritage changes over time, depending on the seasons and age. The team also found that several of the inherited microbiome traits in baboons are also heritable in humans.

“The environment plays a more important role in the configuration of the microbiome than your genes, but what this study does is move us away from the idea that genes have a very small role in the microbiome to the idea that genes have a widespread, albeit small, role, ”said Elizabeth Archie, a professor in the Department of Biological Sciences and lead researcher on the study, which is also affiliated with the Eck Institute for Global Health and the Environmental Change Initiative. .

The intestinal microbiome does several jobs. In addition to helping digest food, it creates essential vitamins and helps train the immune system. This new research is the first to show a definitive connection to heritability.

Previous studies of the intestinal microbiome in humans showed that only 5 to 13 percent of microbes were heritable, but Archie and the research team hypothesized that low numbers resulted from an “instantaneous” approach. to study the intestinal microbiome: All previous studies only measured microbiomes ready in time.

In their study, the researchers used fecal samples from 585 Amboseli wild baboons, typically with more than 20 samples per animal. The microbiome profiles of the samples showed variations in the diet of baboons between wet and dry seasons. Samples collected include detailed information about the host, including known descendants, data on environmental conditions, social behavior, demographics and diet at group level at the time of collection.

The research team found that 97 percent of the features of the microbiome, including overall diversity and abundance of individual microbes, were significantly heritable. However, the percentage of heritability seems much lower (up to only 5%) when samples are tested from a single point, as is done in humans. This emphasizes the importance of studying samples from the same host over time.

“This really suggests that in human labor, part of the reason why researchers haven’t found that heritability is because in humans they don’t have a decade and a half of fecal samples in the freezer and they don’t have all the initial (individual) host information they need to provoke those details, ”Archie said.

The team found evidence that environmental factors influence the heritability of traits in the intestinal microbiome. The heritability of microbiomes was typically 48 percent higher in the dry season than in the wet season, which is explained by the more diverse diet of baboons during the rainy season. Heritability also increased with age, according to the study.

Because the research also showed the significant impact of the environment on the intestinal microbiomes of baboons, their results coincided with previous studies that showed that environmental effects on intestinal microbiome variation play a larger role than the effects genetic additives. Combined with the discovery of the genetic component, the team plans to refine their understanding of the environmental factors involved.

But knowing the genes in the gut microbiome are heritable opens the door to the identification of microbes in the future that are modeled by genetics. In the future, therapies could be tailored to people based on their genetic makeup intestinal microbiome.

The Amboseli Baboon Project, started in 1971, is one of the longest studies on wild primates in the world. Focusing on the savannah baboon, the project is located in the Amboseli ecosystem of East Africa, north of Mount Kilimanjaro. Research teams have tracked down hundreds of baboons in various social groups throughout their lives. Researchers currently control about 300 animals, but have amassed information about the life stories of more than 1,500 animals.