International Space Station isn’t bacteria-free, NASA study shows

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The International Space Station (ISS) is as much of an home to bacteria and pathogens as it is to astronauts, NASA has revealed through a new study.

The findings are the results of DNA analysis carried out by researchers at NASA’s Jet Propulsion Laboratory who found that there are bacterial pathogens aboard the ISS, which could result in inflammations or skin irritations. NASA wasn’t able to tell whether the pathogen are harmful to astronaut health or not, but it did say that the findings will enable it to ensure better cleanliness of the space station in the future.

Using state-of-the-art molecular analysis of the samples from the ISS that involved latest DNA sequencing technologies, NASA scientists were able to rapidly and precisely identify the microorganisms present in the ISS dust samples. NASA says that the latest tests it carried out allowed its scientists to fill the gaps left by traditional methods and were able to highlight the pathogens that may pose a threat to astronauts.

For the testing, NASA used samples obtained from air filter and vacuum bag dust from the ISS. Scientists also carried out similar tests on samples collected from NASA ‘cleanrooms’ – environmentally controlled and closed built spaces on Earth – and compared the results.

NASA says that some of the key differences between the cleanrooms and the ISS are the cleanrooms circulate fresh air while the ISS filters and recirculates air, and the ISS is inhabited continuously with only six people while 50 people may be in a cleanrooms in a day but not inhabit it continuously. Whilst these Earth cleanrooms are not air-tight, they have several layers of rooms that would prevent free exchange of air particulates.

Researchers analyzed the samples for microorganisms, and then stained their cells with a dye to determine whether they were living or dead. Using this technique they were able to measure the size and diversity of viable bacterial and fungal populations, and determine how closely the conditions in the Earth cleanrooms compare with the ISS environment.

The findings suggest that Actinobacteria, a type of bacteria associated with human skin, made up a larger proportion of the microbial community in the ISS than in the cleanrooms, which the authors conclude could be due to the more stringent cleaning regimes possible on Earth.

Two groups of opportunistic pathogens that can lead to infections were also found in the ISS dust samples, but the research did not address the virulence of these pathogens in closed environments or the risk of infection to astronauts.