Researchers said that the amounts of fungi and bacteria found on the ISS are considerably larger than those in the JPL’s cleanrooms on Earth.
Study authors also found some strains of bacteria that may sicken ISS crew members. NASA researchers and other experts have been keeping an eye on the orbital laboratory’s microbiome for 15 years. Researchers gathered dust samples from surfaces and air vents, grew the bugs under strict conditions, and analyzed the samples both on the ISS and in NASA laboratories.
Yet, the study has some limitations. NASA researchers explained that some types of bacteria and fungi cannot be bred in laboratories, making them underepresented in previous research.
NASA is especially interested in bacteria humans carry to space because it plans to soon send humans to planet Mars. But in the process, bacteria may also come along and disrupt the natural environment on the Red Planet.
In the recent study, researchers mapped the DNA of all ISS microorganisms including those than cannot grow in artificial conditions. This time, scientists analyzed two types of samples.
One was taken from an air-vent that had been functioning for more than 40 months. The other one was taken from a vacuum cleaner which is used by ISS crew members to clean surfaces abroad the floating space laboratory.
DNA tests showed that most of microbiome found on the ISS stems from human skin. This is why so little of these bacteria were found in Earth’s carefully controlled cleanrooms. Additionally, some of the bugs were potentially harmful to humans especially if they have weak immune systems.
Kasthuri Venkateswaran, the lead author of the study and researcher at NASA’s Jet Propulsion Laboratory, explained that in microgravity the human body undergoes some changes that may compromise the immune system. And because trillions of microbes inhabit the International Space Station, weakened immune systems may allow bacteria to lead to disease.
Nevertheless, Venkateswaran added that the bacteria have the potential to lead to disease, but it doesn’t mean that they would. For instance, it is not enough to have one of two virulent microbes to have a disease. Virulent microorganisms are those that generate toxins.