U. researchers use fecal transplants to help rats eat toxic plants

Published: Monday, July 21 2014 12:50 p.m. MDT

A captive desert woodrat, also known as a packrat, stands on a rock near branches from a toxic creosote bush. A new University of Utah study shows how microbes in the gut play a key role in letting mammals such as woodrats digest and survive on creosote, juniper and other toxic plants. The researchers used antibiotics to kill gut microbes, rendering creosote-eating woodrats unable to digest the plant. They also transplanted feces from woodrats that ate creosote into woodrats that ate juniper. That transplanted fecal gut microbes gave the latter woodrats the ability to digest creosote.

University of Utah

SALT LAKE CITY — Woodrats from northern Utah were better able to eat toxic plants after receiving microbe-filled fecal transplants, according to a new study by the University of Utah.

The study, published Monday in the journal "Ecology Letters," confirms a long-held suspicion that bacteria in the gut play a crucial role in allowing herbivores to eat toxic plants, according to Kevin Kohl, a postdoctoral researcher at the University of Utah.

"For decades, scientists have thought that gut microbes or gut bacteria might help mammals eat poisonous plants, but there really hasn’t been a thorough test of that idea," Kohl said. "We conducted a series of experiments to show this was the case."

For the study, which was funded by the National Science Foundation, researchers observed how well woodrats — or packrats — from different regions of the state were able to consume Creosote, a toxic shrub found in southern Utah.

Kohl said that rats from St. George commonly eat Creosote and when their fecal matter was transplanted into rats from the north, those animals were better able to digest the Creosote toxins.

"Our northern or Tooele animals can’t eat that plant as well, but when we ground up the poop from our St. George animals and fed it to the animals that we collected near Tooele, we could increase their ability to feed on these toxins," Kohl said.

Kohl said fecal transplants are common in the medical field, where enemas are used to move fecal matter from one person to another.

But for the study, researchers integrated the fecal matter into the rats' food, which is already a common part of a woodrat diet.

"We decided to feed the feces to our woodrats," Kohl said. "They do this by themselves. They eat their own feces, or poop, all the time. So what we did is we collected feces and ground it up and mixed it into their food so they would have to eat it."

Kohl said the research has applications in the breeding and grazing of livestock, as well as implications for aggressive plant species that overtake an ecosystem.

He gave the example of Juniper, which is expanding its range in Utah and is generally too toxic for livestock to eat.

"There’s been big interest in getting sheep and goats to eat Juniper," Kohl said. "We think some of these principles could be translated to other plants with different types of toxins and that we could hopefully transplant these bacteria into other species."

He also said the research suggests that animals that are bred in captivity, or given antibiotics to promote growth, might not have the necessary bacteria in their bodies to eat toxic plants that would otherwise be on the menu.

"Our study suggests that a reduced microbiota might impact their ability to feed on poisons," he said. "So these animals that are bred through captive programs and released into the wild might not have the bacteria that they need."

Kohl said the research is currently working with Juniper consumption and is limited to rodents. He said in the future he hopes to see the work shift to larger mammals, like sheep or goats.

Email: benwood@deseretnews.com, Twitter: bjaminwood

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