Microbial Survival in Spacecraft Assembly Clean Rooms and Protected Landscapes

The ability to go dormant under stress may help microbes survive some of the most extreme conditions on—and off—Earth.

By Madhan Tirumalai, Madison Parker, Sahar Ali, George E. Fox, and William R. Widger

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About this article

This article was first published online on March 31, 2026, as part of the Picturing the Unseen series.

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The interior of a cave in Carlsbad Caverns National Park. Bacteria and other microbes inhabit unique places like these in several U.S. national parks, where they may experience total darkness and other challenging conditions. Scientists think such microbes could give clues about what to expect in the extreme environments of spacecraft and other planets.

NPS / Max Bray

Microbes—bacteria, fungi, and other microscopic organisms—are everywhere. When you take a stroll in a park, go diving in the ocean, or crawl into a cave, these invisible forms of life are with you. People spend a lot of time removing microbes from environments where they can cause problems, like hospitals and the controlled "clean rooms" used to assemble spacecraft. The latter are some of the cleanest places humans build.

But some microbes can survive by going dormant, remaining alive but temporarily inactive. When conditions improve for them, they revive and resume growth. This has implications for the safety of patients and astronauts, and the integrity of data collected from space exploration. That survival strategy may also help shape the fragile park ecosystems some of these microbes inhabit.

Similar Extremes

In laboratory studies, several of us recently showed that Tersicoccus phoenicis, a bacterium found in spacecraft assembly clean rooms, can enter a dormant state when stressed by a lack of nutrients or moisture. Such dormant microbes raise concerns about controlling contamination on the International Space Station. They could also compromise the ability of scientists to reliably detect signs of life on the Moon, Mars, and other celestial bodies.

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In these extreme park environments, microbes often experience long periods of nutrient scarcity, darkness, and other conditions not conducive to growth.

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These microbes are not unique to clean rooms. Many of the same microbial groups found there, particularly the Actinobacteria, are also widespread in national parks. They inhabit lava tubes, glacial lakes, desert soils, and cave systems. There, they quietly influence mineral formation, water quality, and soil fertility. In these extreme park environments, microbes often experience long periods of nutrient scarcity, darkness, and other conditions not conducive to growth. These conditions are strikingly similar to those in spacecraft clean rooms­­—and possibly on other planets.

The Grinnell Glacier basin in Glacier National Park in 2012. Ice cold glacial lakes like this one may have distinct communities of microorganisms that change over time.

NPS / Tim Rains

To see what we could learn from this analogy, we researched published studies from Carlsbad Caverns National Park, Great Basin National Park, Lava Beds National Monument, El Malpais National Monument and other protected areas. The studies identified Actinobacteria as key components of cave and lava-tube microbiomes. In some cases, they represented more than 10–25 percent of detected microbial communities. Similar microbial community patterns were reported in cold, nutrient-poor glacial and alpine lake systems. There, dormant or slow-growing microbes help cycle nutrients and support ecosystem function.

Other Ways to Survive

But dormancy may not be as crucial to microbial survival in extreme natural systems as it is in built ones. Hazel Barton, a leading cave microbiologist who studies the microbes in Carlsbad Caverns, said, “Most cave microbes are used to harsh environments.” So they may have little need to go into protective dormancy. Such microbes have other ways to survive. Cave-dwelling Actinobacteria, for example, produce antifungals and antimicrobials. This may confer protection against fungi or bacteria to animals, like bats, that live in caves. As bats are susceptible to the devastating white-nose syndrome, a fungal disease, this discovery has implications for protecting their populations.

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“A deeper understanding of the roles Actinobacteria play and how they affect our cave ecosystems is critical.”

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Though dormancy is only one survival strategy microbes use, it may still be important to consider when determining how to protect certain unique park places and wildlife. Dormant microbes can stay alive but invisible for long periods. So shifts in temperature or moisture, airflow, or accidental contamination may have effects that are not immediately detectable.

Staff or visitors’ clothing and equipment can influence cave microbial communities by introducing microbial spores. Microbes like Actinobacteria that go dormant may spread unseen from one part of an ecosystem to another, with undesirable effects. As Superintendent Christopher Mengel of Lava Beds National Monument said, “A deeper understanding of the roles Actinobacteria play and how they affect our cave ecosystems is critical.”

Each year, national park biologists check bats—important consumers of agricultural pests—for diseases such as white-nose syndrome. Research on cave-dwelling microbes shows that bats may naturally acquire chemical tools to fight back against this and other deadly diseases.

NPS / Hollie Pucket

Complementary Observations

If dormancy is a factor, knowing how and when microbes “switch on” after periods of inactivity may help managers develop long-term monitoring strategies in fragile park environments. Insights gained from highly controlled laboratory studies of clean-room microbes can thus complement field-based observations in parks. They offer a new lens through which to interpret microbial resilience, recovery, and ecosystem function in protected landscapes.

In the future, we hope to study Earth analog sites like Lava Beds National Monument to aid efforts already underway to determine whether caves on Mars could preserve microbial evidence of past life. We expect this research would also give insights that benefit parks in their work to preserve these unique places.

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They may hold mysteries as intricate as the vast expanse of the cosmos and as important as the next live-saving drug.

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The next time you stand under the dark sky in a national park and look at the shining stars, meteors, and Milky Way, consider the microbes hidden beneath your feet. Deep inside caves, they have survived for thousands of years. They may hold mysteries as intricate as the vast expanse of the cosmos and as important as the next live-saving drug.

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Acknowledgments

The work described in this article was supported in part by National Science Foundation Award NSF-MCB-EAGER-2227347 to Madhan Tirumalai and George E. Fox, and by a University of Houston Drug Discovery Institute (DDI) seed grant awarded to Madhan Tirumalai and William Widger.

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About the authors

All authors are affiliated with the Department of Biology and Biochemistry at the University of Houston in Houston, Texas.

Research Professor Madhan Tirumalai, PhD, studies microbial evolution, environmental microbiology, bacterial dormancy, and response to stress. Photo courtesy of Madhan Tirumalai. Used with permission.

Madison Parker is a graduate student. She is studying the actinobacterium Micrococcus luteus. Photo courtesy of Madison Parker. Used with permission.

Sahar Ali is a graduate student studying actinobacterial dormancy and resuscitation. Photo copyright © University of Houston. Used with permission.

Emeritus Professor and Research Professor George E. Fox, PhD, is the co-discoverer of the Archaea. Photo copyright © University of Houston. Used with permission.

Professor William R. Widger, PhD, has a broad interest in microbial dormancy pathways. Photo copyright © University of Houston. Used with permission.

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Republishing this article

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Cite this article

Tirumalai, Madhan, and others. 2026. “Microbial Survival in Spacecraft Assembly Clean Rooms and Protected Landscapes.” National Park Service, March 31, 2026. https://www.nps.gov/articles/000/psv40n1_microbial-survival-in-spacecraft-assembly-clean-rooms-and-protected-landscapes.htm