Expedition Six Flight Engineer Don Pettit uses a chemical/microbial analysis bag to collect water samples from the Potable Water Heater in the Zvezda Service Module on the International Space Station. (NASA)
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To monitor microbial growth and ensure a safe and healthy environment on the International Space Station, crew members take regular samples of air, surfaces, and water to be analyzed. Scientists' main focus is still to prevent microbes on the station, rather than to remediate. (NASA)
View large image Staying clean in a world full of germs is an important part of our daily lives. We regularly wash and bathe - knowing that these rituals help keep us healthy and prevent illness from spreading. But we still host millions of tiny organisms all over our bodies all the time, and they're not all bad either.
These microscopic creatures, called microbes, are constant companions to every part of our Earth. Many microbes play important roles in the delicate balance of different biological environments, or ecosystems. An ecosystem can be a part of a person (like the gastrointestinal tract), the entire body or many people living together. It can be a speck of dirt or an entire planet. Every ecosystem, big or small, creates a new opportunity for microbes to live, die, multiply or change and to impact its fragile environment.
The microbial ecosystems on the International Space Station are no different. Some microbes were inhabitants from the time the station was assembled. Some join each time a new crew member or payload arrives. People, their habits, their physiological reactions to their emotional states, and their physical environment are all variables that have the potential to continue to alter microbe systems on the space station. With the potential to affect future space exploration missions, researchers funded by NASA's Human Research Program plan to gather and analyze biological samples to study better the space station's Microbiome - the ever-changing microbe environment that can be found on the space station and its inhabitants.
Researchers are asking important questions: how might microbes aboard the station impact an astronaut living in space for a year or more? Could an extended period of spaceflight create an influx of disease-causing germs known as pathogens, or affect a crew member's ability to fight off a disease? What would be the potential effects to station hardware or its operation? Could it be a show-stopper for long-duration space travel? The old adage holds true: an ounce of prevention is worth a pound of cure. So, as plans continue toward exploring space further and longer, NASA researchers are looking for answers to these questions and others.
NASA has a long history of studying the microorganisms that inhabit the closed-environments of spacecraft, such as the study of specific measurable characteristics called microbial biomarkers, which indicate the physiological state of organisms as they are spread among the crew members and their spacecraft environment. Until now, however, NASA has not conducted a systematic, comprehensive study using the latest molecular technology of the microbiome of the crew members or their environment. Among the station's microbes are pathogens that are introduced in a variety of ways. For example, humans naturally carry Staphylococcus aureus (more commonly known as "staph"), so it's not surprising that this bacterium has been found on surfaces and in the air on the station where crew members live and work. Opportunistic pathogens (such as waterborne bacteria) could cause very serious, sometimes fatal infections. Crew members could serve as hosts, bringing pathogenic viruses aboard the station with them.
"We spend a great deal of time and effort to prevent pathogens from getting aboard spacecraft," says Mark Ott, Ph.D., a microbiologist at NASA's Johnson Space Center, Houston. "So, we are definitely interested in possible changes in the types of organisms on spacecraft over time, which result from the crew's exposure to the spaceflight environment."
A crew member's diminished immune system also can make infection more probable, so precautionary measures are put in place to protect them. Crew members receive medical exams before launch. Water and air aboard the station are filtered, and microbe levels (including on surfaces) are regularly sampled and monitored. Payloads are reviewed to ensure all biohazardous materials are adequately contained, and food lots are carefully analyzed before transport. The host-pathogen relationship aboard the station's environment is pivotal in the battle between health and disease; therefore, it is important that crew members maintain a healthy, robust immune system during their time aboard the space station. In the upcoming Microbiome study, a team of scientists led by Hernan Lorenzi, Ph.D., assistant professor at the J. Craig Venter Institute in Rockville, Md., plans to gather and analyze microbial air, surface and water samples from the station and saliva, blood, skin and perspiration samples from several crew members before, during and after their missions. Crew members will even provide gastrointestinal samples gathered during trips to the bathroom!
Each bodily sample contains different collections of bacterial species that are likely to be affected by environmental factors associated with space travel. For instance, skin microbes are expected to be more susceptible to space radiation, while the composition of the gut and mouth microorganisms (or flora) may be more affected by changes in an astronaut's diet. Data from these collections will help scientists understand the status of the crew members' microbiome, its interaction with the unique environment of the space station and which environmental factors associated with space travel are most likely to alter the normal composition of the human microbiome.
There also is intense study of the microbiome by the U.S. and other countries following the finding that it is linked to the state of health in different organs and tissues. Performing this study in the stressful environment of space will allow scientists to determine whether alterations in the crew's microbiome are harmful to human health.
For example, do microbes inhabiting the air of the space station end up being part of the astronauts' nose microbiome? And if so, do these newly acquired bacteria pose a potential risk to the crew members' health by displacing beneficial microbes from the nose? Answers gathered from this and other related studies are expected to provide bold new knowledge on the health effects of stress on out health on Earth, and will be critical for developing preventive treatments that diminish the chances of becoming sick during long stays in space.
Impairment of immune function or introduction of disease from pathogens could have drastic consequences for the safety of the crew members and the success of a mission. The ability to assess the likelihood and consequences of changes in the microbiome due to extreme environments and the related health risks posed to humans also may benefit populations on Earth. This study may provide key factors to expanding our fragile horizon into space, while expanding the knowledge base for how the human body's microbiome functions.