Gut microbes alter the metabolism of mice to help the animals to adapt to the cold.

Mirko Trajkovski of the University of Geneva, Switzerland, and his team studied mice that were kept at low temperatures, and found that their microbiomes diverged from those of mice housed at room temperature. When microbes from cold-exposed mice were transplanted to those without any bacteria, the recipients made more beige fat cells, which burn more energy to produce heat than white fat cells do. The transplants also improved the recipients' metabolism by boosting their insulin sensitivity. Both cold exposure and transplants increased the absorptive surface of the gut, enhancing caloric uptake.

The microbiome's control over energy expenditure could make it a therapeutic target for combating obesity, the researchers suggest.

Cell 163, 1360–1374 (2015)