Woodrats Feast on Toxic Plants, Thanks to Gut Microbes

Woodrats can "stomach" just about anything, even toxic creosote bushes, thanks to helpful gut microbes, a new study published in the journal Ecology Letters found.

Numerous plants produce toxic chemicals, which they use as a defense mechanism against herbivores like woodrats (Neotoma lepida) native to western North American deserts. For these creosote bush-munchers - a plant that is abundant in the region, along with juniper - they have to watch out for the chemical nordihydroguaiarectic acid (NDGA) that wreaks havoc on the liver and kidneys of other lab mice. For any critter that eats these harmful foods, they require a mechanism that helps protect them from the toxic chemicals that the plants produce every day.

Researchers suspect that 17,000 years ago woodrats somehow acquired novel toxin-degrading gut microbes to adapt to climate and vegetation changes, thereby allowing them to digest poisonous plants.

"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. We conducted a series of experiments to show this was the case," Kevin Kohl, a postdoctoral researcher at the University of Utah, said via Uncover California.

In this study, Kohl and colleagues performed three experiments using two kinds of woodrats--juniper eaters from the Great Basin desert and creosote eaters from the Mojave Desert. They were captured and kept in the lab on a diet of rabbit chow.

They decided to incorporate fecal matter into their rabbit feed.  Feces is actually already part of a woodrat's normal diet.

After ingesting feces - and thus gut microbes - from creosote eaters, juniper eaters persisted for 11 days on the creosote diet without losing much weight. This means that the woodrats were able to eat the potentially harmful creosote plant to their heart's content thanks to the transplanted gut microbes. Meanwhile, 65 percent of the juniper eaters that ate feces of other juniper eaters didn't gain microbes that detoxify creosote, so they lost 10 percent of their weight by day 11 on a creosote diet.

Additionally, woodrats that didn't get transplants of creosote-detoxifying microbes had more acidic urine, suggesting their livers expended a lot of energy to degrade creosote toxins.

Researchers say that these findings could potentially impact farming practices in arid regions where toxic plants are abundant. And though insightful, the concept of fecal transplants is nothing new. In the medical field, enemas are often used to transfer fecal matter from one person to another.