Whether your gut microbiome changes is dependent on what's already in there

Hundreds to thousands of microbial species live in your gut microbiome, “affect(ing) our health, fertility and even our longevity,” the Carnegie Institution for Science informs.

Researchers were curious as to how the bacterial communities comprising our individual gut microbiomes got there in the first place, then designed and carried out a study – which recently got published online in the Proceedings of the National Academy of Sciences.

What they discovered may have “major implications for treatments,” a news release says, “such as faecal transplants and probiotic administration.”

“There is a huge amount of variation in microbiome composition between individuals,” William Ludington of Carnegie Institution for Science explains.

“For example, if you look at the sum total of all of the bacterial species that are adapted to live in the gastrointestinal systems of humans, most of these are not present in a majority of people. That’s how incredibly diverse these gut microbial populations are.”

While a combination of elements determine our microbiomes, they don’t directly have a say in the species that “successfully colonise” our guts. Chance has a lot to do with it, and the researchers were trying to figure out what factors help with the colonisation process.

The scientists used germ-free fruit flies (drosophila melanogaster) to demonstrate that being exposed to a microbial species does not mean that it will successfully become part of the fly’s microbiome.

What they discovered was that “the state of the microbiome, and interactions between existing microbiome member species, sets the odds for whether a newly encountered bacteria is added into the mix.”

“Even among genetically identical flies that lived in the same housing and were fed the same diets, we saw variations in microbiome composition,” David Sivak of Simon Fraser University says.

The researchers came up with mathematical models that would set up complex scenarios of microbiome species acquisition, “leading to their breakthrough understanding of the community factors that shape membership in the microbiome ecosystem,” the news release notes.

“Think of microbiome composition as a big party where the social dynamics determine who leaves early and who stays until dawn,” says Ludington.

Eric Jones, the paper’s first author, also of Simon Fraser University adds that “Bacterial colonisation depends on a number of complicated factors that we’re just starting to understand.  

We showed, for example, that some groups of species facilitate each other’s colonisation and are therefore more likely to coexist.”

The research has interesting results that would be able to suggest to healthcare professionals how to adjust a person’s microbiome towards a preferable composition.

“The beauty of the mathematical approach we deployed is that it acknowledges that colonisation is a roll of the dice, but we are now able to attribute the weighting of the dice to biological interactions with a molecular basis that has been honed by evolution,” says Jean Carlson of UC Santa Barbara.

The researchers write that “Our approach revealed that acquisition events are stochastic,” suggesting that they have, according to Oxford Languages, “a random probability distribution or pattern that may be analysed statistically but may not be predicted precisely.”

They add that their findings “have consequences for microbiome-based therapies” such as “faecal microbiota transplantation” which involves modifying an individual’s gut biome by introducing foreign microbes on purpose.

THUMBNAIL IMAGE: Artist's concept of this research that probes the odds of a new species being acquired by a microbiome ecosystem created by Navid Marvi, courtesy of the Carnegie Institution for Science.

Source: TRTWorld and agencies