Microbes from Human Skin Have Colonized the ISS

When astronauts travel to the International Space Station, they carry trillions of microbial hitchhikers with them. Over the years, these tiny organisms have developed their own colonies on the station, which are examined in unprecedented detail in a new study published today in the journal Microbiome.

Researchers led by Kasthuri Venkateswaran, a molecular biologist at NASA's Jet Propulsion Laboratory, studied dust particles collected from ISS vacuums and air filters and compared them to samples collected from NASA cleanrooms. Their efforts mark the first time any team has combined both traditional techniques, like colony counts, with advanced genetic sequencing of the station's microbial communities.

This comprehensive approach has exposed several microbial groups that seem to escape the astronauts' cleaning regimens on the ISS. The main offenders hailed from the Actinobacteria, Firmicutes, and Proteobacteria families, all of which are associated with the human skin microbiome.

"The results of this study provide strong evidence that specific human skin-associated microorganisms make a substantial contribution to the ISS microbiome," the team said, "which is not the case in Earth-based cleanrooms."

According to Venkateswaran, the study is intended to establish a baseline model for keeping tabs on the microscopic astronauts inhabiting the station alongside their human vessels. This will not only help to ensure that harmful pathogens can be identified and eradicated, but will hopefully also provide a solid framework for assessing cleanliness on even more ambitious manned missions, to the Moon, asteroids, Mars and beyond.

"This background information will enable the building of future microbial monitoring technologies," Venkateswaran told me over email. "The future approach is to develop 'DNA microarray' or related sensors to measure the abundance of the problematic microorganisms so as to develop countermeasures."

Indeed, as evidenced by the gross fungal and bacterial that spread throughout the Mir space station, keeping space habitats clean is a crucial priority for manned space exploration. This isn't just an issue for human exploration, as NASA is also concerned that rovers sent to investigate cool planetary finds, like that Martian water discovered last month, might contaminate samples with Earth-based microbes.

While it's wonderful that humans are striking out to explore new cosmic frontiers, it's becoming increasingly clear that we need to regulate the tiny accidental astronauts that tag along.