Giant Pandas Don't Have the Gut Bacteria to Properly Digest Bamboo

Giant pandas may munch on bamboo, but it turns out that their gut bacteria aren't designed for that meal. Scientists have discovered that the gut bacteria of giant pandas can't efficiently digest bamboo.

"Unlike other plant-eating animals that have successfully evolved anatomically specialized digestive systems to efficiently deconstruct fibrous plant matter, the giant panda still retains a gastrointestinal tract typical of carnivores," said Zhihe Zhang, lead author of the new study, in a news release." The animals also do not have the genes for plant-digesting enzymes in their own genome. This combined scenario may have increased their risk for extinction."

Pandas evolved from bears that ate both plants and meat. However, they began to start eating bamboo exclusively about two million years ago. Today, the animals spend up to 14 hours daily consuming up to 27.5 pounds of bamboo leaves and stems. However, it appears as if the animals can digest only about 17 percent of their food intake; their feces are actually mainly composed of undigested bamboo fragments.

Intrigued by this, the researchers decided to evaluate the panda gut microbiota. The scientists used 16S rRNA sequencing on fecal samples from giant pandas. In the end, the scientists found that the giant pandas had extremely low gut microbiota diversity. Not only that, but the overall structure was similar to carnivorous and omnivorous bears and did not harbor plant-degrading bacteria.

"This result is unexpected and quite interesting, because it implies the giant panda's gut microbiota may not have well adapted to its unique diet, and places pandas at an evolutionary dilemma," said Xiaoyan Pang, one of the researchers.

Pandas are currently endangered, and there are only an estimated 1,600 left in the wild. This makes it especially important to understand how diet can affect these animals.

The findings are published in the journal mBio.

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