After hearing about kangaroo rats at a brown bag science event a few years ago, geotechnical engineer Idil Akin became fascinated with the rodents.
The assistant professor in Washington State University’s Voiland College of Engineering and Architecture spent the next several months reading everything she could about the cute-but-tough little creatures. Of particular interest was the way they build elaborate and highly durable burrows from sand that last for generations under the harshest climate conditions on Earth.
For someone who studies the use of soil as a construction material, Akin wants to know how they do it. She suspects the rats may be mixing bacteria into the sand to make it sturdier and if that’s the case wonders if those techniques could be emulated by humans in building structures for a harsher climate in the future.
A three-year, National Science Foundation grant is enabling Akin to explore that hypothesis. The $640,000 award will be one of the first that considers kangaroo rats as synergistic bio-geotechnical engineers in a relatively new field of study called bioinspired geotechnical engineering, Akin said.
“I think this project is borderline between crazy and cool,” she said.
Biologists have long been fascinated by kangaroo rats because of their unique metabolisms and their ability to live for an extended period of time without water, Akin said. The rodents are commonplace in southwestern deserts of the US. Akin started learning about the creatures at about the time that she had the chance to visit an extreme climate — the Atacama Desert in South America.
“I started thinking about these extreme desert conditions with temperature and relative humidity fluctuations and flash flooding events, and yet somehow, these animals manage to keep these burrows stable under these extreme conditions,” she said.
In her studies, she also learned that the burrow homes are microbial hotspots. That is, as the rats collect and eat food, they grow bacterial communities in their cheek pouches and on their feet. As they move through their burrows, they build up a slimy microbial community throughout their home. For the new grant, Akin is studying these microbial communities to determine if they might contribute to the stability and longevity of the burrow structures in extreme conditions.
“When I learned about these microbial hotspots, I got so excited about this project that I couldn’t stop talking about it,” Akin said. “With climate change, we are seeing more and more extreme environments, and we need to be ready for these extreme environments. If these animals can do it with a material that they produce, can we learn from them? If we can learn from them, then perhaps we can improve our geotechnical structures and designs before we experience worse conditions.”
For the study, the researchers will collect microbial samples from the kangaroo rats and then grow them in sandy soil in a lab to create a kind of microbial muddy cement. They will test the soil’s strength and mechanical and hydraulic behavior under different temperature, humidity, and saturation conditions. Akin is collaborating with an interdisciplinary team on the project, including Haluk Beyenal, a professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, who studies microbial biofilms, and Clint Collins, assistant professor in biology from Sacramento State University.
For all the fun of learning about a cute rodent, Akin’s dive into the world of kangaroo rats has given her a new perspective on her years of research and studies in geotechnical engineering.
“For many goetechnical engineers, soil is our construction material — We either build on it or build something with soil,” she said. “Thinking about other animals, microbes, and creatures in the soil is a perspective that I didn’t have in my studies. Now I think about those things – soil is not just a construction material anymore for me.”
