Photo credit NASA
Researchers from the Astromaterials Research and Exploration Science Division at NASA Johnson Space Center conducted a study to determine the optimal duration for microbial air sampling in their curation cleanrooms. Given the value and sensitivity of the astromaterial samples, agar and liquid-based samplers are avoided to prevent contamination and false positives in life detection tests. Instead, they used the AirPrep Bobcat Sampler, which employs a dry electret filter for collection, a rapid Wet Foam Elution system, and a high flow rate.
The study involved comparing 72 pairs of air samples collected at 200 liters per minute for 1 hour and 17-hour durations across six cleanrooms: the meteorite processing lab, the lunar lab, the stardust lab, the OSIRIS-REx lab, the Hayabusa2 lab, and the Genesis lab. These labs represent ISO 4, 5, 6, and 7 cleanroom standards.
Only two out of 72 samples had no amplifiable DNA. On average, the longer, 17-hour samples had slightly more DNA sequences than the 1-hour samples, but the difference was not statistically significant. Longer collection times resulted in slightly higher microbial diversity without biasing towards more resilient bacteria, like spore-formers.
The study concluded that sampling at least 3,000 liters of air is sufficient to capture microbial diversity, and overnight air sampling does not negatively impact this diversity.
“These results allow us to be flexible when designing microbial monitoring plans so that they do not interfere with routine lab activity.”
Read the report –
Does Collection Time Bias the Ecology of Cleanroom Air Samples? Regberg et al.
NASA Technical Reports Server 2024
