Extreme bacteria on the Space Station are evolving to deal with harsh conditions, not to make astronauts sick


For years, scientists have conducted studies aboard the International Space Station (ISS) to determine the effects of space life on humans and microorganisms. In addition to high levels of radiation, there are also concerns that prolonged exposure to microgravity may cause genetic mutations. Understanding them and proposing countermeasures is essential for humanity to become a truly spatial species.

Interestingly, a team of Northwestern University researchers recently conducted a study of bacteria that were kept aboard the ISS. Contrary to what many have suspected, bacteria have not turned into a drug-resistant super-strain, but mutated to adapt to their environment. These results can be vital when it comes to understanding how living beings will adapt to the stressful environment of space.

The study describing the team's discovery appeared recently in mSystems, a scientific journal published by American Society of Microbiology. The study was conducted by Erica Hartmann, an assistant professor in the Department of Civil and Environmental Engineering (DCEE) at NWU, and included several postdoctoral and postdoctoral researchers from the DCEE and Sarah Castro-Wallace of the NASA Johnson Space Center.

Scientists have experimented to see how bacteria grow in space. Credit: NASA

Studies like this are essential for missions planned for the near future, which include NASA's plans to renew missions to the lunar surface and the proposed manned mission to Mars. In addition, China, Russia and India also plan to send astronauts to the moon in the coming decades. As Professor Hartmann explained in a NWU press release:

"There has been much speculation about radiation, microgravity and lack of ventilation and how this can affect living organisms, including bacteria. These are stressful and severe conditions. Does the environment select superbugs because they have an advantage? The answer seems to be no. "

For the sake of their study, Hartmann and his associates consulted data from the National Biotechnology Information Center (NCBI), which maintains archived information on experiments with microbes conducted aboard the ISS. Specifically, they evaluated how the bacteria Staphylococcus aureus and Bacillus cereus grew in space.

The first is found in human skin and contains the drug resistant strain MRSA, which makes it responsible for several difficult to treat infections in humans. The latter lives on the ground and has few implications for human health, but has produced valuable information about how terrestrial microbes grow when they are removed from their comfort zone and subjected to unfamiliar conditions in space.

20,000-fold increase in drug-resistant staphylococcal aureus bacteria. Credit: CDC

"The bacteria that live on the skin are very happy there," Hartmann said. "Your skin is hot and has certain oils and organic chemicals that bacteria really like. When you bring down these bacteria, they find themselves living in a very different environment. The surface of a building is cold and sterile, which is extremely stressful for certain bacteria. "

When the team compared how these strains grew on board the ISS on how the same strains grow on Earth. What they discovered was that the bacteria living on the ISS mutated to adapt to local conditions, selecting genes advantageous to be able to continue to feed, grow and function in microgravity and when exposed to higher levels of radiation.

Ryan Blaustein, a postdoctoral fellow at Hartmann's laboratory who was the first author of the study, indicated that this was a surprising result. "Based on genomic analysis, it appears that bacteria are adapting to live – not evolving to cause disease," he said. "We did not see anything special about antibiotic resistance or virulence in the bacteria of the space station."

This is certainly good news for future astronauts, not to mention people hoping to join the burgeoning space tourism industry some day. In both cases, crews are forced to live, work and usually pass the time in tiny capsules or modules where there is no ventilation and the air circulates for long periods of time.

The artist's concept of a bimodal nuclear rocket that makes the trip to the Moon, Mars and other destinations in the Solar System. Credit: NASA

Given the health risks, knowing that terrestrial bacteria do not turn into supergermes that are even more resistant to antibiotics is certainly a relief. Of course, Hartmann and his colleagues also emphasized that this study does not mean that germs can not proliferate when they enter a spacecraft or aboard a space station:

"Wherever you go, you bring your microbes with you. Astronauts are extremely healthy people. But as we talk about the expansion of space flight for tourists that do not necessarily meet the criteria of the astronauts, we do not know what will happen. We can not say that if you put someone with an infection in a closed bubble in space, it will not be transferred to other people. It's like when someone coughs up on an airplane and everyone gets sick.

As always, space exploration presents many risks, and the prospect of sending astronauts on longer journeys or tourists to space presents many challenges. Fortunately, we have decades of research to support and many cutting-edge experiments to help us inform us before this day arrives.

This study was made possible with the support of the Searle Leadership Fund and the National Institutes of Health (NIH).

Further reading: Northwestern University, mSystems


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