Study finds that microbial dispersal impacts animal guts

October 3, 2017, University of Oregon
Zebrafish

In a special experiment, zebrafish with defective immune systems swam and dined with counterparts with normal immune systems. In short order, their gut microbiomes became similar.

The experiment at the University of Oregon was designed to test, at a fundamental level, the impact of microbial dispersal among individuals with different microbiomes.

The eight-member team concluded "that inter-host dispersal can alter the diversity and composition of microbial communities and overwhelm the effects of the host's innate immune system." The findings, the team wrote, "suggest that dispersal is an important mechanism driving variation."

The study was published Oct. 2 in the online early edition of the Proceedings of the National Academy of Sciences.

"We have long known that diseases can be caused by the movement of between individuals, but the microbiome has rarely been approached this way," said microbiologist Brendan Bohannan, a professor of biology and member of the UO Institute of Ecology and Evolution. "We were curious if the transmission of microbes is enough to explain the variation that we see in the microbiome composition among individual fish."

The National Institutes of Health-supported research was done in the UO's META Center for Systems Biology. META refers to microbial ecology and theory of animals. The center studies how host-microbe systems work and how that knowledge may advance human health.

For the study, the researchers created a line of zebrafish with defective immune systems by inserting a mutation into a gene required for development of an important component of the immune system.

The fish were maintained under three conditions: individual fish housed alone with no exposure to others; fish cohoused in groups of either immune-compromised members or wild-type individuals; or mixed groups of fish with both immune-compromised and wild-type individuals together. After 21 days, researchers examined the in each fish's intestines and those associated with their food and the surrounding water.

The team, led by doctoral student Adam R. Burns, now a postdoctoral researcher at Stanford University, compared what they found in the fish with predictions from computer modeling of microbial dynamics performed by co-author Elizabeth Miller of the META Center for Systems Biology.

Raised separately, Bohannan said, the immune-compromised and the wild-type fish had markedly different microbes in their guts.

"For those raised in a mixed community, their gut composition converged as their microbes were shared," he said. "Most surprisingly, the fish raised in groups of the same kind—immune-defective or immune-competent—also had gut communities similar to those raised in mixed groups. This result suggests that the movement of microbes does more than just mix microbes between different fish, but it also selects for particular microbes that are especially good at moving from fish to fish."

While the study looked only at the ability of to exchange microbes, it suggests that microbiome variation among different people might also be due to the movement of microbes, and that when people come together for a class or a meeting, for example, they may depart with a microbiome that is somewhat different than when they entered, Bohannan said.

Researchers at the UO and elsewhere had previously suggested that shared environmental spaces could lead to the sharing of microbes, he said. "Those studies, however, couldn't rule out other explanations for the similarities that emerged. For example, in our previous studies of the built environment, we never showed it worked as a means of transmission; it showed that there were enough human-related microbes to make it possible."

Explore further: Thousands of new microbial communities identified in human body

More information: Adam R. Burns et al, Interhost dispersal alters microbiome assembly and can overwhelm host innate immunity in an experimental zebrafish model, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1702511114

Related Stories

Thousands of new microbial communities identified in human body

September 20, 2017
A new study of the human microbiome—the trillions of microbial organisms that live on and within our bodies—has analyzed thousands of new measurements of microbial communities from the gut, skin, mouth, and vaginal microbiome, ...

Study suggests some gut microbes may be keystones of health

November 11, 2015
University of Oregon scientists have found that strength in numbers doesn't hold true for microbes in the intestines. A minority population of the right type might hold the key to regulating good health.

Human immune system shapes skin microbiome

October 29, 2013
Our skin plays host to millions of beneficial and potentially disease-causing microorganisms; however, whether our immune system influences these microbial communities to prevent disease is unknown. In a study published online ...

Recommended for you

A gut bacterium as a fountain of youth? Well, let's start with reversing insulin resistance

November 16, 2018
Move over Bifidobacterium and Lactobacillus. There's a new health-promoting gut bacterium in town, and it's called Akkermansia muciniphila.

New inflammation inhibitor discovered

November 16, 2018
A multidisciplinary team of researchers led from Karolinska Institutet in Sweden have developed an anti-inflammatory drug molecule with a new mechanism of action. By inhibiting a certain protein, the researchers were able ...

Pets can double as asthma antidote

November 16, 2018
(HealthDay)—The "hygiene hypothesis" holds that early exposure to a variety of microorganisms may decrease the risk for chronic inflammatory diseases, like asthma.

New study shows NKT cell subsets play a large role in the advancement of NAFLD

November 16, 2018
Since 2015 it has been known that the gut microbiota could have a direct impact on nonalcoholic fatty liver disease (NAFLD), which affects up to 12% of adults and is a leading cause of chronic liver disease. In the November ...

Defense against intestinal infection in organism is affected by prostaglandin E2

November 15, 2018
The treatment of intestinal infections caused by some strains of the bacterium Escherichia coli, present in unsanitized or contaminated foods, may have a new ally.

No link between 'hypoallergenic' dogs and lower risk of childhood asthma

November 15, 2018
Growing up with dogs is linked to a lower risk of asthma, especially if the dogs are female, a new study from Karolinska Institutet and Uppsala University in Sweden shows. However, the researchers found no relation between ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.