Bacteria help pandas make better use of nutrients

This is what a panda does when they hide their treats 0:55

(CNN) -- 

Pandas are famous for being picky eaters.

They only consume bamboo;

a poor-quality, low-fat diet.

But these creatures appear to have evolved to make the most of what they eat, according to a new study.

Your gut bacteria change in late spring and early summer, when bamboo is most nutritious, as protein-rich green shoots sprout.

The bacteria cause the bear to gain weight and store more fat, which the researchers say can make up for a lack of nutrients later in the year, when bamboo plants only have fibrous leaves to chew on.

A panda named "Happiness" feeds on a bamboo shoot in the Foping Nature Reserve, Shaanxi province, China, in 2013. Samples of the panda's droppings were collected for this study.

"We have long known that these pandas have a different gut microbiota during the sprout-eating season, and it is very apparent that they are fatter during this time of year," said study lead author Guangping Huang, a researcher at the Institute of Zoology. of the Chinese Academy of Sciences, in a press release.

The study was published Tuesday in the academic journal Cell Reports.

To investigate how gut bacteria might affect panda metabolism, the team first collected feces from eight wild giant pandas in China's Qingling Mountains during the leaf-eating season and shoot-eating season and then examined the differences between the samples. of excrement.

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They found that a bacterium called Clostridium butyricum was more abundant in the pandas' intestines during the season when they enjoy fresh bamboo shoots.

To find out if this bacterium helps bears gain and store weight, the researchers performed a fecal transplant, putting the panda's excrement into laboratory mice.

They then fed the mice for three weeks a bamboo-based diet that simulated eating by pandas.

Although mice are very different from pandas, it was not possible to conduct such tests with endangered and vulnerable animals, said Wei Fuwen, a co-author of the study and a professor at the Key Laboratory of Animal Ecology and Conservation Biology at the Institute of Zoology of the Chinese Academy of Sciences.

Mice were a good substitute.

"Mice has proven to be an effective model to study the function of the gut microbiome in humans," Wei said by email.

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The researchers found that mice transplanted with panda feces collected during the sprout-eating season gained significantly more weight, despite consuming the same amount of food.

"Gut bacteria were the only variable in this investigation," Wei explained.

Felix Sommer, head of the host microbiome functional research group at Christian-Albrechts-University in Kiel, Germany, noted that the number of pandas involved in the study was small and that the experiment had only been performed once.

Sommer, who was not involved in the research, also stressed that the researchers had found a correlation, not a causal relationship, between the bacteria and weight gain.

"I would have asked for some kind of validation experiment or re-sampling at another year or time point," Sommer, who has conducted similar research on hibernating grizzlies, said by email.

Wei said more work is needed to validate the causal relationship directly in pandas.

He added that his work could help improve the health of captive giant pandas.

Panda bear