Houston Daily

University of Houston microbiologists have discovered that a rare bacterium, Tersicoccus phoenicis, can survive the rigorous sterilization processes in NASA spacecraft assembly clean rooms by entering a dormant state. This ability allows the microbe to avoid detection even in environments designed to be nearly free of contaminants.

The research team, led by Madhan Tirumalai from the University of Houston’s Department of Biology and Biochemistry, published their findings in Microbiology Spectrum. The study suggests that this dormancy strategy could have significant implications for how space missions and other sterile environments approach microbial contamination and sterilization.

“These clean rooms are extreme habitats for microbial adaptation and evolution,” said Tirumalai. “These findings highlight the resilience of spacecraft-associated microbes, and it has a huge planetary protection concern.”

Tersicoccus phoenicis was first identified over ten years ago in clean rooms located in Florida and French Guiana. These facilities undergo extensive cleaning protocols to prevent microorganisms from contaminating spacecraft or being transported to other planets.

The UH research group included Professor William Widger, graduate student Sahar Ali, and Emeritus Professor George E. Fox. Their investigation focused on how T. phoenicis manages to persist under such harsh conditions. They found that the bacterium enters a state with very low metabolic activity—essentially "playing dead"—which allows it to survive periods without nutrients.

Widger explained that when his team added a resuscitation-promoting factor—a protein common among actinobacteria—to dormant T. phoenicis cells, the bacteria became active again: “When they added the protein, T. phoenicis cells ‘woke up,’ confirming the bacterium can ‘play dead’ to survive nutrient starvation and possibly resist the stringent conditions in spacecraft clean rooms.”

Dormancy is already known as a survival tactic among actinobacteria; for example, Mycobacterium tuberculosis uses it to withstand hostile conditions until circumstances improve.

Beyond its relevance for space exploration, these findings may affect practices in hospitals, pharmaceutical labs, and food processing plants where undetected dormant bacteria could pose challenges for sterilization protocols.

“I think other industries are missing the idea that these bacteria can evade detection in their clean rooms by going dormant,” Widger said. “We don't know if they're going to be nasty bacteria — they may not be — but it would be nice to know if they're there or not.”

The researchers also noted potential applications for controlling pathogenic bacteria such as those causing tuberculosis. Preventing these organisms from entering dormancy might make them more susceptible to antibiotics or disinfection measures.

“If we can find a way to prevent the bacteria from going latent, maybe the antibiotics could kill it before it goes into dormancy,” Widger said.