Yet another reason to adore giant pandas: Microbes in the animals' feces may help overcome obstacles to producing biofuels, which generate energy from renewable sources.

One such fuel, ethanol, is created by fermenting sugars from corn or sugar cane. Alternative and more environmentally friendly methods can extract sugars from plant fibers (cellulose), but that is an inefficient process that requires the fibers to be treated with heat, pressure or acid.

The giant panda may offer a better solution. Although the animal has a digestive tract that is much shorter than that of other herbivores, microbes in its gut are efficient enough to extract a meal from bamboo.

Researchers are working to harness panda microbes to create biofuels. Using dung samples collected from zoos, Ashli Brown, a biochemist at Mississippi State University, and her colleagues are growing panda-gut flora in the lab, hoping to gain a better understanding of how the microbes work.

There are some hurdles. Because the giant panda is endangered, scientists cannot experiment on the animal itself to find out more about its digestive processes. They have only the poop. "So little is known, it's hard to simulate," said Candace Williams, a graduate student involved in the research.

Williams is trying to determine the optimal conditions in which to grow the microbes, starting them on a diet of glucose, celloboise (two glucose molecules tightly bound together) and cellulose (hundreds of glucose molecules tightly bound together).

"Once that baseline is established," she said, "we'll be able to step up to something more complex, such as switchgrass," a crop that is more environmentally friendly than corn or cane.

Once scientists have identified the panda microbes that are most effective at breaking down cellulose, they can isolate the genes that produce the working enzymes. Genetically engineered yeast cells

Giant panda, ethanol. illustration by Patterson Clark

could then be designed to yield industrial quantities of the enzymes, which could turn corn cobs, wood chips and grass into the clean fuels of the future.

Sources: Journal of Nutrition, Proceedings of the National Academy of Sciences