Giant Panda Stays Plump on Bamboo Diet Thanks to Gut Bacteria

Changes in gut microbiota, that occur as a result of changes in food availability, have long been observed in many animals, including in some monkey species, which in summer eat fresh leaves and fruits, and in winter – bark. A similar shift has also been seen in some human tribes in Tanzania, whose diet changes throughout the year.

Changes in the gut microbiota of pandas during the season when nutritious bamboo shoots become available allow the giant herbivores to gain more weight and store fat, compensating for the lack of nutrients, for example, in seasons when it is only possible to chew bamboo leaves, a new study published in the Cell Reports journal on Tuesday revealed.

"This is the first time we established a causal relationship between a panda's gut microbiota and its phenotype," said one of the co-authors. "We've known these pandas have a different set of gut microbiota during the shoot-eating season for a long time, and it's very obvious that they are chubbier during this time of the year."

A team of researchers from the Institute of Zoology of the Chinese Academy of Sciences, led by Fuwen Wei, sought to determine whether the changes of the microbiota affect metabolism. Scientists carried out a number of experiments on two groups of mice that were transplanted with panda feces, collected during shoot-eating and leaf-eating season, and put them on a “bamboo-based” diet.

The first group of mice gained weight very quickly and had more fat than the second one, despite consuming the same amount of food.

"Causal research of host phenotype and gut microbiota in wild animals is just beginning. Identifying what bacteria are beneficial for animals is very important, because one day we may be able to treat some diseases with probiotics," researchers say.