• Cara Murez
• Posted January 7, 2022

Zoo Study Finds Animal DNA Floating in Air

Take a whiff of the air in a zoo and you could breathe in the animals' DNA -- not just the smell of the food they eat or their waste, a new study suggests.

Sampling the air from local zoos, two teams of researchers collected enough DNA to identify the animals nearby. They say their study could potentially become a valuable, noninvasive tool to track biodiversity.

"Capturing airborne environmental DNA from vertebrates makes it possible for us to detect even animals that we cannot see are there," said researcher Kristine Bohmann, head of the team at the University of Copenhagen in Denmark.

While terrestrial animals can be monitored by trail cameras or checking for footprints or feces, a drawback to these methods is they can involve intensive fieldwork and require the animal to be physically present.

This "environmental DNA," or eDNA, is a well-established technique used most frequently to monitor aquatic organisms by sequencing eDNA from water samples.

"Compared to what people find in rivers and lakes, monitoring airborne DNA is really, really hard, because the DNA seems super diluted in the air," said Elizabeth Clare, lead researcher of the Queen Mary University of London team. "But our zoo studies have yet to fail for different samplers, genes, locations, and experimental approaches. All of it worked and surprisingly well," said Clare, who is now at York University in Toronto.

The two groups published their "proof of concept" research Jan. 6 in the journal Current Biology.

Each team conducted its individual studies at a local zoo, collecting samples in both walled-in areas like the tropical house and indoor stables and outdoor, open-air enclosures.

To collect airborne eDNA, the Copenhagen team used a fan, like one used to cool down a computer, and attached a filter to it. The fan draws in air from the zoo and its surroundings. This could contain genetic material from breath, saliva, fur or feces, though the exact source has not been determined.

After air filtration, they extracted the DNA from the filter and used PCR amplification to make a lot of copies of the animal DNA, the researchers said. They processed the millions of DNA sequences and compared them to a DNA reference database to identify the animal species.

The samples contain forensically tiny amounts of DNA, Clare said in a journal news release.

Clare's team detected DNA from 25 species of mammals and birds from inside the zoo and wildlife nearby. Bohmann's team detected 49 non-human vertebrate species, including mammal, bird, reptile, amphibian and fish species.

It's coincidence that researchers in two locations came up with the same idea at the same time, but after seeing each other's articles on a preprint server, the two groups decided to submit their manuscripts to the journal jointly.

"We decided we would rather take a bit of a gamble and say we're not willing to compete on this," said Clare. "In fact, it's such a crazy idea, we're better off having independent confirmations that this works. Both teams are very eager to see this technique develop."

More information

The U.S. Department of Agriculture has more on wildlife research.

SOURCE: Cell Press, news release, Jan. 6, 2021