Science - August 14, 2014

Gut flora have tipping points too

Rob Ramaker

Certain intestinal bacteria seem to swing rapidly from being in plentiful supply to being scarce. Insight into this ‘switch’ could help restore disturbed gut flora to health.

Photo: Filip Bunkens

Wageningen researchers Leo Lahti, Marten Scheffer and Willem de Vos and several Finnish colleagues of theirs wrote about this in the journal Nature Communications on 8 July.

In conditions such as obesity and type 2 diabetes, the gut flora is often disrupted so that an unusual species of bacterium may dominate. This knowledge is generating new treatments. For example, patients with a persistent bowel infection stand the best chance of recovery if they are given a whole new gut flora through a ‘poop transplant’. For targeted disease control, however, scientists need to find out more about how our network of gut bacteria works.

New treatments

In their study the researchers prove that populations of gut bacteria are prone to tipping points. According to Scheffer’s tipping point theory, ecosystems are usually found in a stable state (with an abundance of bacterium x) which provides resistance to change.

When an influence from outside has enough impact, the system ‘tips’, however, to an alternative balance (in which bacterium x is scarce). ‘That this applies among the gut flora is completely new,’ says Willem de Vos, professor of Microbiology.

That this applies among the gut flora is completely new
Willem de Vos

The changes to the stable balance are health-related. In the elderly, for instance, some groups of bacteria tip much more easily towards a situation in which they are plentiful. De Vos reckons there are many more associations to be discovered. And they offer starting points for new treatments.

Dominant species

For the study, the intestinal flora of more than 1000 people from 15 western countries was analysed. The researchers then identified 130 groups of micro-organisms, based on their genetic material.

Remarkably, the tipping of individual bacteria types did not cause major changes in other groups. Working on the basis of his experience with other ecosystems, however, professor of Aquatic Ecology Marten Scheffer thinks this must be possible. ‘Something like that can happen when a very dominant species tips the balance.’  He points out that the current trial only looked at healthy individuals and not yet at patients.