(Ivanhoe Newswire) – To win a war, the perfect strategy must be executed. The gut has been doing just that, carrying out a discrete strategy that tips the scales of microbial wars that occur inside of every animal, including humans. A new study shows that the gut actively selects whichever microbes are the best partners for the body, and nurtures them with nutritious secretions.

 

"The cells of our bodies are greatly outnumbered by the microbes that live on us and, in particular, in our gut," said Professor Kevin Foster of Oxford University's department of Zoology, an author of the paper.

 

Many microbes found in the gut are highly beneficial, protecting the body from pathogens and helping it with digestion, he said. 

 

“Quite how such a beneficial mutual relationship evolved, and how it is maintained, has been something of a mystery," Foster said.

 

A team of researchers created an evolutionary computer model of interactions between gut microbes and the lining, or epithelial cell layer, of the host animal’s gut. The model showed that some beneficial microbes are slow growing, and can be rapidly lost if they are not helped by secretions of the host gut, such as specific nutrients that favor the beneficial microbes over harmful ones.

 

The work also showed the host only needs to use a very small amount of secretions to save the microbes that would otherwise have been lost.

 

"The inside of our gut is rather like a war zone,” said Jonas Schulter, also of Oxford University's department of Zoology and first author of the paper, “with all kinds of microbes battling it out for survival and fighting over territory. Our study shows that hosts only have to secrete a small quantity of substances that slightly favor beneficial microbes to tip the balance of this conflict.”

 

After the secretion occurs, the cells affected not only survive, but grow, pushing other strains out of the body, Schulter said. This is an example of selectivity amplification, or when a small change implemented by the host produces a large-scale effect.

 

The study may have wider implications than the human gut. Selectivity amplification may occur in a range of other interactions between hosts and microbes, including the microbes that grow on the surface of corals and the roots of plants.

 

“This research highlights the importance of growth-promoting substances in our ability to control the microbes that live inside us,” Schulter said. “It shows that nutrients are more powerful when released by the host epithelial cell layer than when coming from the food in the gut, and suggests that controlling our microbes is easier than was previously thought."

 

Source: PLOS Biology, November 20

 

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