Gut bacterium Turicibacter reduces weight gain in mice ^{CEFR B2}

Researchers report that a single gut bacterium, Turicibacter, improves metabolic health and reduces weight gain in mice fed a high-fat diet. The study was published in Cell Metabolism and adds to evidence that the gut microbiome influences weight and metabolic disease.

The team had previously shown that a community of about 100 bacteria could prevent weight gain, but isolating an individual microbe was difficult because many gut bacteria die quickly outside the gut. After years of culturing individual strains, first author Kendra Klag found one rod-shaped bacterium that lowered blood sugar, reduced circulating fats and limited weight gain in mice on a high-fat diet. Senior author June Round said she had not expected a single microbe to have such a dramatic effect.

Turicibacter seems to act by producing thousands of different fatty molecules in a "lipid soup" that the small intestine absorbs. Adding purified Turicibacter fats to a high-fat diet produced the same weight-controlling effects as the live bacterium. The bacterium also influences host ceramide levels; ceramides rise on a high-fat diet and are linked to disorders such as type 2 diabetes and heart disease, and Turicibacter-derived fats help keep ceramide levels low.

The researchers also observed a feedback loop: high dietary fat inhibits Turicibacter growth, so mice on a high-fat diet lose the bacterium unless the diet is regularly supplemented. The authors note that many gut bacteria likely contribute to metabolic health and that results in mice may not apply to humans. They plan further work to identify the active lipids and to test possible therapies. Additional coauthors are from the University of Utah, Washington University School of Medicine and Germany’s Max Planck Institute for Biology, and the work was supported by the National Institutes of Health and several foundations.