Rare clean room bacterium survives by playing dead UH team finds
by Clarence Oxford
Los Angeles CA (SPX) Oct 09, 2025
A University of Houston team reports that a rare bacterium found in NASA spacecraft assembly clean rooms can evade detection by entering dormancy, effectively "playing dead" in a nutrient-poor environment.

The microorganism, Tersicoccus phoenicis, turned up in two clean rooms more than a decade ago in Florida and French Guiana. These facilities undergo rigorous sterilization to protect spacecraft and planetary bodies from contamination.

Lead author Madhan Tirumalai and colleagues in UH's Department of Biology and Biochemistry examined how the non-spore-forming actinobacterium persists under such harsh conditions. Their experiments indicate the organism can switch to an extremely low metabolic state and stop growing.

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

Because related actinobacteria such as Micrococcus luteus can be revived from dormancy by a resuscitation-promoting factor protein, the researchers tested whether T. phoenicis responds similarly. Introducing the protein reactivated cells, supporting the dormancy-and-resuscitation mechanism.

The findings suggest dormant actinobacteria could also hide in hospitals, pharmaceutical plants, and food processing facilities. Improved detection and sterilization strategies may be needed to account for dormancy-based evasion.

"I think other industries are missing the idea that these bacteria can evade detection in their clean rooms by going dormant," said co-author William Widger. "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 work may inform efforts to control pathogenic actinobacteria, including those that cause tuberculosis, by preventing entry into latency and improving the effectiveness of antibiotics. "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.

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