Effects of sugar on beneficial gut bacteria

Effects of sugar on beneficial gut bacteria


As understanding of the role of the gut microbiota in human health expands, researchers have found that diet influences gut microbiomes by providing nutrients to particular species assemblages. Among the species associated with lean and healthy individuals is Bacteroides thetaiotaomicron.

Researchers investigated the effect of a high-fructose diet on B. thetaiotaomicron populations, given that fructose, as well as the monosaccharide glucose, is abundant in the Western diet.

The authors found that the bacteria require a protein called Roc for gut colonization, and that both fructose and glucose decreased the abundance of the Roc protein within 1 hour in bacterial cultures. Incorporation of the roc leader mRNA in front of a heterologous gene was sufficient for fructose and glucose to turn off expression of the corresponding protein.

The authors then engineered a strain of B. thetaiotaomicron resistant to Roc silencing by glucose and fructose, and demonstrated that the strain outcompeted the wild-type strain in mice fed a diet high in glucose and sucrose, a disaccharide composed of glucose and fructose but not in mice fed a complex polysaccharide-rich diet. 

According to the authors, the results suggest that diet can regulate bacterial colonization in the gut, and that the role of diet in the gut microbiota goes farther than merely providing nutrients. 

https://www.pnas.org/content/early/2018/12/12/1813780115

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