Researchers have found that the reason certain microbes seem to survive in all spacecraft clean rooms is that those microbes actually live off the very cleaning fluids used to scrub the rooms.
Despite extensive cleaning procedures, however, molecular genetic analyses show that the clean rooms harbor a diverse collection of microorganisms, or a spacecraft microbiome, that includes bacteria, archaea and fungi, explained Mogul. The Acinetobacter, a genus of bacteria, are among the dominant members of the spacecraft microbiome.
To figure out how the spacecraft microbiome survives in the cleanroom facilities, the research team analyzed several Acinetobacter strains that were originally isolated from the Mars Odyssey and Phoenix spacecraft facilities.
They found that under very nutrient-restricted conditions, most of the tested strains grew on and biodegraded the cleaning agents used during spacecraft assembly. The work showed that cultures grew on ethyl alcohol as a sole carbon source while displaying reasonable tolerances towards oxidative stress. This is important since oxidative stress is associated with desiccating and high radiation environments similar to Mars.
The tested strains were also able to biodegrade isopropyl alcohol and Kleenol 30, two other cleaning agents commonly used, with these products potentially serving as energy sources for the microbiome.
With this information, the space engineering community will be able to refine their clean room operations to eliminate these microbes so as to better sterilize spacecraft heading on life-seeking missions.