One of the world’s most amazing technological inventions, the International Space Station (ISS), is apparently filled with fungi and bacteria. A new study has determined that microorganisms found on the skin of the astronauts in the station are floating throughout the enclosed space. Some of these organisms have the potential to cause serious harm to the astronauts.
NASA goes to great lengths to reduce any likelihood that such microbes will catch a free ride onto the ISS. Payloads delivered to the ISS must go through “clean rooms” that have intense air filtration systems. The loads are also thoroughly scrubbed and cleansed with various disinfectants. However, the ISS itself contains the humans that produce the microbes. Every time an astronaut exercises, eats, uses the bathroom or combs his or her hair, skin cells are shed into the contained, isolated environment. With the shed of skin cells comes the release of microbes into the air.
Concerned about this potential problem, NASA requested that researchers at its Jet Propulsion Laboratory (JPL) assess the situation. In the most comprehensive and thorough search for bacteria and fungi ever done of the ISS, the research team sequenced genetic material found in the dust of an air filter and vacuum cleaner bags that were sent back to Earth. JPL microbiologist Kasthuri Venkateswaran, who led the research team, noted that, “We need to know what we’re breathing in a closed environment. It’s always better to know before things get out of control.”
Venkateswaran and colleagues relied on deep-sequencing machines. They chemically removed cells that did not have complete membranes, thereby increasing the chance that they studied living bugs rather than dead ones. For the past ten years, NASA has swabbed several surfaces in the ISS every three months in order to culture pathogens.
The researchers compared the DNA from pathogens found in the ISS with those collected at two JPL clean rooms. The most troubling thing was what they found in the “high-efficiency particulate arrestance” (HEPA) air filter used in the ISS. Almost 100% of the living DNA sequences they collected came from the Actinobacteria. In contrast, only about 25% of the sequences collected from JPL clean room came from the Actinobacteria.
The high levels of this bacteria is “problematic,” says Venkateswaran, because it contains species that are opportunistic pathogens.
Paula Olsiewski, who runs the Microbiology of the Built Environment program at the Alfred P. Sloan Foundation in New York City pointed out that the research has widespread implications. “People have trouble understanding that we’re embedded in an invisible microbial world.”
Venkateswaran says the research concludes that microbial monitoring clearly needs to become more thorough and more sophisticated in the ISS. “If NASA is going beyond the moon to Mars you need an automated biosensor. I’m giving a background model and showing them these are the common things you can find, and a subset of them are ones where you have to be careful.”