英文科普：人类肠道会选择培养有益细菌

Animals, including humans, actively¹ select the gut² microbes that are the best partners and nurture³ them with nutritious secretions⁴（分泌物）, suggests a new study led by Oxford⁵ University, and published November 20 in the open-access journal PLOS Biology. The Oxford team created an evolutionary⁶ computer model of interactions between gut microbes and the lining⁷ (the host epithelial cell layer) of the animal gut. The model shows that beneficial microbes that are slow-growing are rapidly lost, and need to be helped by host secretions, such as specific nutrients⁸, that favour the beneficial microbes over harmful ones.

 

The work also shows that the cost of such selectivity is low: the host only needs to use a very small amount of secretions to retain beneficial microbes that would otherwise have been lost.

 

"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 Zoology⁹, an author of the new paper. "We know that many gut microbes are highly beneficial to us, protecting us from pathogens and helping¹⁰ us with digestion¹¹, but quite how such a beneficial mutual¹² relationship evolved, and how it is maintained, has been something of a mystery."

 

"This research highlights the importance of growth-promoting substances in our ability to control the microbes that live inside us. It shows that nutrients are more powerful when released by the hostepithelial cell（上皮细胞） layer than when coming from the food in the gut, and suggests that controlling our microbes is easier than was previously¹³ thought."

 

Jonas Schulter, also of Oxford University's Department of Zoology and first author of the paper, said: "The inside of our gut is rather like a war zone, with all kinds of microbes battling it out for survival and fighting over territory. Our study shows that hosts only have to secrete¹⁴ a small quantity of substances that slightly favour beneficial microbes to tip the balance of this conflict: it means that favoured microbial species that would otherwise be lost don't just survive on the epithelial surface but expand, pushing any other strains out."

 

The team's simulations show that cells affected¹⁵ by host epithelial selection are least likely to be lost, and instead persist longest, causing 'selectivity amplification¹⁶', whereby relatively¹⁷ tiny changes instituted by the host (in this case a very small amount of secretions of certain compounds) can be amplified¹⁸ to produce a large-scale effect.

 

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