Opportunistic bacterial pathogens, including those linked to inflammations or skin irritations, have been found living on the International Space Station, according to a study conducted by the U.S. space agency NASA.
"Where there are people, there are bacteria, even in space," NASA said in a statement. "The findings of this study help NASA establish a baseline for monitoring the cleanliness of the space station, which will in turn help manage astronaut health in the future."
Microgravity is known to affect bacteria, and the current thinking is that microgravity is not favorable to bacterial survival generally, but that some species that can withstand it may become more virulent.
Previous studies of the space station have used traditional microbiology techniques, which culture bacteria and fungi in the lab, to assess the composition of the microbial community.
Kasthuri Venkateswaran with NASA's Jet Propulsion Laboratory (JPL) and colleagues have now used the latest DNA sequencing technologies to rapidly and precisely identify the microorganisms present on the space station.
The team compared samples from an air filter and a vacuum bag from the space station with dust from two JPL clean rooms, which are controlled and thoroughly cleaned laboratory environments.
Their results showed that human skin-associated bacteria Actinobacteria made up a larger proportion of the microbial community in the space station than in the cleanrooms, which they said could be due to the more stringent cleaning regimens possible on Earth.
The study also found Corynebacterium and Staphylococcus, two other types of pathogens that are mostly innocuous on Earth but can lead to infections that result in inflammations or skin irritations, are present on the space station.
But the researchers did not address the virulence of these pathogens in closed environments or the risk of skin infection to astronauts.
"Studying the microbial community on the space station helps us better understand the bacteria present there, so that we can identify species that could potentially damage equipment or pose harms to astronaut health," Venkateswaran said. "It also helps us identify areas that need more rigorous cleaning."
According to the U.S. space agency, such research will also be important for long-duration space missions, such as NASA's journey to Mars.
The findings were published Tuesday in the open access journal Microbiome.
