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Jan. 22, 2020
Rest assured, microbes do not, it turns out, become “super bugs” in space.
International Space Station (ISS). Animation Credit: NASA
When humans and equipment go to the International Space Station, microbes such as bacteria and fungi come along for the ride. In the extreme environment, only microbes that are most likely to survive in these conditions thrive. A recent ESA (European Space Agency) study, Extremophiles, found that the resulting microbes are not, however, more resistant to antibiotics or extremophilic – able to thrive in environments previously thought uninhabitable – than those found on Earth in similar conditions.
“The idea we had was to find out whether the microbiome on board the space station is more resistant or more harmful than it would be on ground. Spaceflight causes some crew members to have periods of stress, and we wondered if the microbes would be stressed as well and might react in a bad way,” said the study’s Principal Investigator Christine Moissl-Eichinger of Medical University of Graz, Austria.
To live in orbit above Earth, microbes must deal with exposure to microgravity, radiation, cleaning agents and metal surfaces. The Extremophiles investigation studied the microbiome of the inside of the space station. A recently published paper details the varieties and locations of the station’s microbiome – the community of bacteria, bacteriophages, fungi, protozoa and viruses that live in the environment, as well as on and in the human body. Extremophiles can be dangerous to human health and equipment, and scientists are careful to avoid transferring them to a new environment on a visiting vessel.
Image above: NASA astronaut Jack Fisher wipes designated surfaces in the Cupola with Wet Wipes as part of the Extremophiles investigation. Image Credit: NASA.
“Previous studies indicated that there is high level of resistant genes and a lot of allergy-causing microbes, but [previous research] never put it in context. They never compared the results to similar ground environments,” said Moissl-Eichinger.
Since the station is a closed system, new microbes are introduced through the arrival of new crew, cargo or hardware. A similar environment on Earth is a cleanroom, where access is controlled and staff enters and exits through airlocks, wearing protective clothing to minimize particulate transfer to the cleanroom environment.
ESA researchers compared the station’s microbial community with that of an Earth-based cleanroom that prepares items for the station. This comparison turned out to be key to the investigation’s findings.
“We analyzed two sets of data, comparing data from the station with data from normal ground surroundings,” said Moissl-Eichinger. “We found that microbial virulence was not increased, the resistances were not higher, the microbes were not stressed. We could not see any particular differences.”
As might be expected, most of the microbes on station are those associated with human presence. People literally could not live without these tiny organisms, many of which are beneficial (see Microbiology 101: Where People Go, Microbes Follow). On the station, larger numbers of human-related microbes are found wherever humans more frequently interact with surfaces.
Researchers found that after almost 20 years of continuous human presence, the space station has developed a core microbiome of 55 different microorganisms. Even though the quantities change over time, the long-term mix of biological material is stable.
“We have a lot of samples from the station which now are more than 15 years old,” said Moissl-Eichinger. “There is a group of microorganisms you can detect in any sample that you are analyzing from the space station. Obviously, these microbes are surviving very well,” said Moissl-Eichinger.
Image above: For the Genes in Space-3 experiment, the Biomolecule Sequencer demonstrates using portable, real-time DNA sequencing to assay microbial ecology, diagnose infectious diseases, and monitor crew health aboard the space station. Image Credit: NASA.
The one significant difference between the station microbiome and that of the ground areas studied had to do with microbes’ reactions to metal surfaces.
Some microbes respond negatively to station surfaces, potentially creating biofilms or corrosion. Experience with Russia’s Mir space station showed that some microbes, especially fungi, can become “technophilic,” or technology-loving, resulting in growth on metal areas, wiring connectors and inside panels. These communities caused the progressive destruction of a window on Mir as well as electrical outages. Since such microbes require wet conditions, it is important to keep metal surfaces dry.
Benefitting from the experience of Mir, designers of the space station ensured that the station does not have areas that collect moisture and are inaccessible to maintenance activities. Despite the dry environment, samples from the space station showed the presence of some technophiles.
“We found indications that the microbes are adapting to the surfaces on board. These microbes were really different to those that we found on the ground. These technophilic organisms are attacking the surfaces as they struggle to stay alive,” Moissl-Eichinger explained.
Going forward, the researchers recommend continuing to keep surfaces dry and conducting periodic sample collection. They also highlighted the potential benefits of equipment capable of identifying microbes in space without return to Earth or the use of cultures, such as the Biomolecule Sequencer, currently being used for the Biomolecule Extraction and Sequencing Technology (BEST) investigation. With quick-turnaround information, crew members could target areas of concern when needed rather than stressing microbes by constant cleaning.
After all, as Moissl-Eichinger explained, “We need our microbes.”
Related links:
Extremophiles: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7370
The Extremophiles investigation paper: https://www.nature.com/articles/s41467-019-11682-z
Microbiology 101: Where People Go, Microbes Follow: https://www.nasa.gov/mission_pages/station/research/news/microbiology-101-space-station-microbes-research-iss
Biomolecule Sequencer: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1917
Biomolecule Extraction and Sequencing Technology (BEST): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7687
European Space Agency (ESA): https://www.esa.int/
Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html
International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html
Animation (mentioned), Images (mentioned), Text, Credits: NASA/Michael Johnson/JSC/International Space Station Program Science Office/Carrie Gilder.
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