Bears' seasonal hibernation linked to changes in gut microbes

Date: February 4, 2016

Source: Cell Press

Each year, as bears prepare to hibernate, they gorge themselves on food to pack on fat. And yet, despite the rapid weight gain, the animals somehow avoid the health consequences so often associated with obesity in humans. Now, researchers reporting in Cell Reports on February 4 show that the bears' shifting metabolic status is associated with significant changes in their gut microbes.

Fredrik Bäckhed of the University of Gothenburg in Sweden, who led the new study, said he was particularly struck by the discovery that the bears' summer gut microbiota includes microbes that take in more energy from the diet.

"The restructuring of the microbiota into a more avid energy harvester during summer, which potentially contributes to the increased adiposity gain without impairing glucose metabolism, is quite striking," he said.

Bäckhed and his colleagues showed more than 10 years ago that the composition of the gut microbiota can influence the amount of energy harvested from the diet. Much more recently, they found that the microbiota also shifts in people who are obese and in those with type 2 diabetes. That led them to wonder whether changes to the microbiota might also be important in hibernating brown bears in the wild.

Read on ...

Fecal transplants let packrats eat poison

Woodrats lost their ability to eat toxic creosote bushes after antibiotics killed their gut microbes. Woodrats that never ate the plants were able to do so after receiving fecal transplants with microbes from creosote-eaters, University of Utah biologists found.

The new study confirms what biologists long have suspected: bacteria in the gut – and not just liver enzymes – are "crucial in allowing herbivores to feed on toxic plants," says biologist Kevin Kohl, a postdoctoral researcher and first author of the paper published online today in the journal Ecology Letters.

The study of woodrats, also known as packrats, raises two concerns, according to Kohl and the study's senior author, Denise Dearing, a professor and chair of biology:

Endangered species may lose diversity of their gut microbes when they are bred in captivity. When they are released to the wild, does that leave them unable to consume toxic plants that once were on their menu?

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