(Davis, Calif.) —

Microbiologists at the University of California, Davis who analyzed swabs taken by astronauts on the International Space Station (ISS) and compared them with samples from homes on earth as well as the Human Microbiome Project found that the microbial community in this unique habitat was very diverse and more closely resembled that of homes than of humans.

This study, titled “A microbial survey of the International Space Station (ISS),” was published today in PeerJ, an award-winning open-access journal that publishes research on the biological, medical and environmental sciences.

Research part of Project MERCURRI, a citizen science project



This work was part of a nationwide citizen science project called Project MERCCURI. The project is a collaboration between UC Davis and other organizations including Science Cheerleader, a group of current and former professional cheerleaders pursuing careers in science and math.

Previous research from the same Project MERCCURI team sent 48 bacterial isolates collected around the country to the ISS and described a bacteria that grew better in space than on Earth.

Now the researchers analyzed bacteria found on 15 ISS locations and highlighted some of the thousands of species they found. They then compared their data on the species to published data sets from two other projects: the “Wildlife of Our Homes,” study, which evaluated home microbiomes, and surveys of human body sites from the Human Microbiome Project.

Not more "gross" than bacteria at home

“So ‘is it gross?’ and ‘will you see microbes from space?’ are probably the two most common questions we get about this work,” said author David Coil, a microbiologist in the Department of Medical Microbiology and Immunology at UC Davis School of Medicine. “As to the first, we are completely surrounded by mostly harmless microbes on Earth, and we see a broadly similar microbial community on the ISS. So it’s probably no more or less gross than your living room.”

Regarding finding microbes from space, “Since the ISS is completely enclosed, the microbes inside the station come from the people on the ISS and the supplies sent to them,” he said.

Jenna Lang, former postdoctoral scholar at UC Davis and lead author on the study, agreed.

“The microbiome on the surfaces on the ISS looks very much like the surfaces of its inhabitants, which is not surprising, given that they are the primary source,” she said. “We were also pleased to see is that the diversity was fairly high, indicating that it did not look like a ‘sick’ microbial community.”

Jonathan Eisen, professor of medical microbiology and immunology and of ecology and evolution at UC Davis and another author on the study, believes Project MERCURRI studies have a lot of value.

“Studying the microbial diversity on the ISS is not only of relevance to space exploration but also serves as an important comparison to buildings on Earth because the ISS has many novel features such as limited influx of microbes,” he said.

Project MERCCURI was coordinated by Science Cheerleader, SciStarter, and UC Davis, in conjunction with the Argonne National Laboratory. The project was supported by funds provided by Space Florida, NanoRacks, and the Alfred P. Sloan Foundation.