assessed the succession and persistence of microbial communities and the associated antimicrobial resistance and virulence properties based on metagenomic reads obtained from samples of three flights. Other publications focused on the detection of antimicrobial resistance genes aboard the ISS and evaluated the potential risk these genes might represent in a closed spacecraft environment 22. A study investigating the growth behavior of nonpathogenic (terrestrial) bacteria aboard the ISS found no changes in most bacteria, given that they have enough nutrients 21. Except for cargo exchange and the arrival of new crew members roughly every 6 months, the ISS is completely sealed off from any biological ecosystem 12.Īnalyses of the ISS microbiome have already been performed, including microbial analyses of ISS debris and dust 13, 14, 15, 16, the study of the astronauts’ microbiome 17, the characterization of bacterial and fungal isolates from the ISS 18, 19, and the (molecular) microbial analysis of swab and wipe samples taken inside the ISS 20. The ISS orbits Earth ∼400 km above ground and is meanwhile constantly inhabited for more than 18 years. However, the International Space Station (ISS) has, like no other currently available testbed for long-term manned space missions, the scientific benefit of providing real spaceflight conditions, including microgravity and an elevated background radiation.
The majority of information with respect to environmental microbiome composition and dynamics aboard manned spacecraft is retrieved from ground-based simulation studies, such as the Mars500 11 and the HI-SEAS ( ) experiments.
![clean space station clean space station](https://cdnb.artstation.com/p/assets/images/images/017/586/357/large/alex-whitt-whitt-00-project-2.jpg)
Specifically, Bacillus, Penicillium, and Aspergillus species were associated with the progressive destruction of a window in MIRs descent module 9, and mold on wiring connectors was associated with electrical outages 10. Technophilic microorganisms caused major problems on the former Russian space station MIR, partaking in damage to structural materials as well as malfunctioning of various space systems and equipment 7, 8. Some microorganisms might even pose a risk to the material integrity of a spacecraft: So-called technophilic microorganisms, in particular fungi, are able to corrode alloys and polymers used in spacecraft assembly 6. Another stressor for the indigenous microorganisms is the strict maintenance regime, which could result in an increase of antimicrobial resistances, as recently shown for highly-maintained, confined built environments 5. These include a potentially increased infection risk, as it has been shown that microgravity affects the virulence of certain microorganisms, such as Salmonella typhimurium 3, Listeria monocytogenes, and Enterococcus faecalis 4. Several risks with respect to microorganisms and human spaceflight have been identified. Our body’s microbiome is prone to external factors, including the environmental microbiome, as they are in constant exchange and interaction. Adding an order of complexity, human health is intertwined with its microbiome, billions of microorganisms thriving on external and internal surfaces of the human body. The human immune system was shown to be compromised under space flight conditions, as a significant decrease of lymphocytes and also of the activity of innate and adaptive immune response was observed 1, 2. Maintenance of crew’s health during a several hundred days journey in a confined artificial environment in space is one of the key aspects, which has to be addressed. Human space exploration beyond boundaries of Earth and Moon is a declared goal of NASA, ESA, Roscosmos and other space-faring agencies, envisaging a potential human Mars mission in the next 20–30 years.
![clean space station clean space station](https://iss.jaxa.jp/kids/en/life/images/7_1.jpg)
Our results do not raise direct reason for concern with respect to crew health, but indicate a potential threat towards material integrity in moist areas. The genomic and physiological features selected by ISS conditions do not appear to be directly relevant to human health, although adaptations towards biofilm formation and surface interactions were observed.
![clean space station clean space station](https://cdn.eteknix.com/wp-content/uploads/2016/06/The-International-Space-Station-is-the-first-step-to-a-solar-system-wide-internet-system-800x531.jpg)
We show that the ISS microbial communities are highly similar to those present in ground-based confined indoor environments and are subject to fluctuations, although a core microbiome persists over time and locations. We assess microbial diversity, distribution, functional capacity and resistance profile using a combination of cultivation-independent analyses (amplicon and shot-gun sequencing) and cultivation-dependent analyses (physiological and genetic characterization of microbial isolates, antibiotic resistance tests, co-incubation experiments). Here, we report the results of the ISS experiment EXTREMOPHILES, including the analysis of microbial communities from several areas aboard at three time points. The International Space Station (ISS) is a unique habitat for humans and microorganisms.