Binary bacteria "bits" in human intestines associated with health status

July 17, 2014 by Lisa Zyga, Medical Xpress feature
Five binary bacteria groups (rows) co-occur in various combinations in the 1,006 subjects (columns) in the study. The most frequent combination (18%) corresponds to the high-abundance states of the B. fragilis and two groups of uncultured Clostridiales combined with the low-abundance states of the Dialister spp. and Prevotella groups. Credit: Lahti, et al. ©2014 Nature Communications

The human gut contains hundreds of different types of bacteria, which vary widely among individuals. Understanding these variations is a complex and relatively new area of research. Now in a new study, researchers have found that some bacteria in the gut are distributed in a somewhat surprising way: they are bistable, meaning that most people either have very large numbers of these bacteria or nearly none at all. Some of these bistable bacteria groups are associated with individual factors, such as obesity, metabolic syndrome, irritable bowel syndrome, and age—making these bacteria groups potential targets for microbiome-based diagnostics and therapies.

The researchers, Leo Lahti, et al., from universities in Finland and The Netherlands, have published their study on bistable abundance distributions of certain bacteria groups in a recent issue of Nature Communications.

"While we have not investigated causal relations, our findings suggest that targeted manipulation of specific bacterial groups could be used to affect health, instead of ecosystem-wide perturbations," Lahti, from the University of Helsinki and Wageningen University, told Phys.org. "A key impact of our work is that it simplifies the understanding of the variability in the gut ecosystem and opens up novel opportunities for research on therapeutic manipulation and diagnostics (as individuals can be categorized based on unique combinations of these bistable bacterial populations)."

In their study, the researchers analyzed fecal samples from 1,000 individuals from Europe and the United States. They found that several out of the 130 genus-like bacterial groups they studied exhibit robust bimodal abundance distributions.

As the researchers explain, bistable bacteria can be thought of as bacteria "switches" that have states of either "0" (absence) or "1" (abundance), in analogy to binary computer switches that also have states of "0" or "1." Just as the states of computer switches can be controlled, the states of bacteria "switches" might also one day be controlled by interventions in order to address related health issues.

Another interesting observation was that, when individuals had intermediate amounts of these bistable bacterial groups, the intermediate levels were unstable and tended to "flip" toward either the "0" or "1" state. In other words, the bistable states of the bacterial groups seem to be divided by tipping points, where even small fluctuations may lead to an abrupt shift to a stable state.

The researchers also observed significant associations between the bistable groups and other health factors, as well as co-occurrences among various groups. For example:

  • The high-abundance states of Bacteroides fragilis and Dialister spp. groups were associated with a low gene richness and metabolic dysfunction.
  • The high-abundance states of the Prevotella group (specifically, relatives of P. melaninogenica and P. oralis) and two groups of uncultured Clostridiales were associated with a high gene richness and healthy metabolic phenotytpe.
  • The high-abundance states of the two uncultured Clostridiales groups were also associated with a low body mass index (BMI), a strong overall bacterial community diversity, as well as older age.
  • The low-abundance states of the two uncultured Clostridiales groups were associated with and severe obesity.
  • The most frequent combination of bistable bacteria groups corresponds to the high-abundance states of the two uncultured Clostridiales groups and B. fragilis, combined with the low-abundance states of the Dialister spp. and Prevotella groups.

When investigating how diet may affect the bistable bacteria states, the researchers found that, while short-term dietary interventions did cause state shifts in some individuals, the changes were not statistically significant. This was due to the fact that there was a large amount of within-state variation in other individuals, masking the strong effects of the dietary intervention in certain invidiuals. These results hint at the possibility that targeted dietary interventions could be potentially used to manipulate specific bistable groups in the future. The researchers plan to address this possibility in future research.

"Our present study was based on normal western adults across a relatively short time span of a few months," Lahti said. "Following more closely the long-term temporal dynamics of the bistable bacteria, and analyzing their behavior in different age groups, ethnic populations and disease cohorts will be useful to understand in more detail how these bacteria are associated with host factors and health. In particular, we are now investigating the effects of diet and individual variation."

Explore further: Bacterial switches in the human gut pave way for therapeutic manipulation

More information: Leo Lahti, et al. "Tipping elements in the human intestinal ecosystem." Nature Communications. DOI: 10.1038/ncomms5344

Related Stories

Bacterial switches in the human gut pave way for therapeutic manipulation

July 9, 2014
The microbial ecosystem in the human gut can switch from one stable state into another, without staying for a long time in between. Key groups of bacteria tend to be either nearly absent, or relatively abundant in any given ...

TB lung infection causes changes in the diversity of gut bacteria in mice

May 13, 2014
Johns Hopkins researchers have found evidence in mice that a tuberculosis (TB) infection in the lungs triggers immune system signaling to the gut that temporarily decreases the diversity of bacteria in that part of the digestive ...

When good gut bacteria get sick

July 11, 2014
Being sick due to an infection can make us feel lousy. But what must the ecosystem of bacteria, or microbiota, colonizing our guts be going through when hit with infection? A study from Brigham and Women's Hospital (BWH) ...

Bacteria on your hands reflect the country you live in

May 12, 2014
(Medical Xpress)—Where and how you live strongly influences both the type and number of microbes you carry on your hands, according to a new international study led by scientists at Yale and Stanford.

Recommended for you

New imaging technique can spot tuberculosis infection in an hour

August 16, 2018
Guided by glowing bacteria, researchers have devised an imaging technique that can diagnose live tuberculosis in an hour and help monitor the efficacy of treatments. That's particularly critical because many TB strains have ...

Research shows it's possible to reverse damage caused by aging cells

August 15, 2018
What's the secret to aging well? University of Minnesota Medical School researchers have answered it- on a cellular level.

This matrix delivers healing stem cells to injured elderly muscles

August 15, 2018
A car accident leaves an aging patient with severe muscle injuries that won't heal. Treatment with muscle stem cells from a donor might restore damaged tissue, but doctors are unable to deliver them effectively. A new method ...

Male tobacco smokers have brain-wide reduction of CB1 receptors

August 15, 2018
Chronic, frequent tobacco smokers have a decreased number of cannabinoid CB1 receptors, the "pot receptor", when compared with non-smokers, reports a study in Biological Psychiatry.

Byproducts of 'junk DNA' implicated in cancer spread

August 14, 2018
The more scientists explore so-called "junk" DNA, the less the label seems to fit.

Doctors may be able to enlist a mysterious enzyme to stop internal bleeding

August 14, 2018
Blood platelets are like the sand bags of the body. Got a cut? Platelets pile in to clog the hole and stop the bleeding.

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.