A recently published study reveals that a bacterium discovered in NASA’s clean rooms, known as Tersicoccus phoenicis, has the remarkable ability to enter a dormant state, raising concerns about potential contamination of Mars missions. This microbe, first identified in 2007 in two distinct clean rooms located 2,500 miles (4,000 kilometers) apart, has demonstrated an unexpected resilience against rigorous sterilization processes.
NASA’s clean rooms are designed to eliminate contamination risks during spacecraft preparation. This involves extensive procedures such as heating, chemical treatments, and ultraviolet exposure to ensure that no Earthly microbes accompany missions intended to explore extraterrestrial life. Despite these measures, T. phoenicis not only survived but evaded detection during sterilization checks. The bacterium was officially reported in 2013, with NASA asserting that it posed no health risks to astronauts or missions.
Understanding Dormancy and Survival
The recent findings, published in the journal Environmental Microbiology, provide new insights into the survival mechanisms of T. phoenicis. The research team, led by microbiologist Madhan Tirumalai from the University of Houston, discovered that the bacterium can “play dead” as a survival strategy. In an experiment, the team deprived the bacteria of nutrients and placed them on sterile glass Petri dishes, effectively simulating extreme conditions. Within 48 hours, the bacteria showed signs of dormancy, remaining inactive for a week.
Even after attempts to revive them by reintroducing nutrients, the bacteria remained in a dormant state. However, when exposed to specific proteins, their biological functions resumed, indicating that they were not dead but merely in a state of suspended animation. According to Nils Averesch, a microbiologist at the University of Florida who was not involved in the study, this ability makes the microbial survival on spacecraft surfaces more plausible than previously considered.
Potential Implications for Mars Missions
One of the clean rooms where T. phoenicis was first discovered was involved in preparations for the Phoenix Mars lander, which successfully reached Mars. This raises questions about whether these resilient microbes could have inadvertently been transported to the Martian surface. While the idea is concerning, experts, including Averesch, believe the likelihood of survival on Mars is low. He noted that “anything directly exposed on the Martian surface is unlikely to survive,” due to the planet’s harsh conditions.
Interestingly, the paper suggests that T. phoenicis may have evolved specifically to thrive in the unique environment of spacecraft clean rooms, as it has not been found in any other natural setting. This discovery not only highlights the extraordinary adaptability of microorganisms but also offers valuable insights for improving sterilization techniques in cleanroom environments. Understanding how to coax bacteria out of dormancy could enhance cleaning strategies to ensure the integrity of future space missions.
The findings underscore the remarkable resilience of the smallest forms of life, challenging our understanding of microbial survival and adaptation in extreme environments. As research continues, scientists remain vigilant about maintaining the cleanliness of space exploration efforts to avoid contamination and ensure the integrity of scientific discoveries on other planets.
