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ATP as a biomarker of viable microorganisms in clean-room facilitiesA new firefly luciferase bioluminescence assay method that differentiates free extracellular ATP (dead cells, etc.) from intracellular ATP (viable microbes) was used to determine the viable microbial cleanliness of various clean-room facilities. For comparison, samples were taken from both clean-rooms, where the air was filtered to remove particles >0.5 microm, and ordinary rooms with unfiltered air. The intracellular ATP was determined after enzymatically degrading the sample's free ATP. Also for comparison, cultivable microbial populations were counted on nutrient-rich trypticase soy agar (TSA) plates. Both the cultivable and ATP-based determinations indicate that the microbial burden was lower in clean-room facilities than in ordinary rooms. However, there was no direct correlation between the two sets of measurements because the two assays measured very different populations. A large fraction of the samples yielded no colony formers on TSA, but were positive for intracellular ATP. Subsequently, genomic DNA was isolated directly from selected samples and 16S rDNA fragments were cloned and sequenced, identifying nearest neighbors, many of which are known to be noncultivable in the media employed. It was concluded that viable microbial contamination can be reliably monitored by measurement of intracellular ATP, and that this method may be considered superior to cultivable colony counts due to its speed and its ability to report the presence of viable but noncultivable organisms. When the detection of nonviable microbes is of interest, the ATP assay can be supplemented with DNA analysis.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Venkateswaran, Kasthuri
(Jet Propulsion Lab., California Inst. of Tech. Pasadena CA United States)
Hattori, Noriaki
La Duc, Myron T.
Kern, Roger
Date Acquired
August 21, 2013
Publication Date
March 1, 2003
Publication Information
Publication: Journal of microbiological methods
Volume: 52
Issue: 3
ISSN: 0167-7012
Subject Category
Life Sciences (General)
Distribution Limits
NASA Discipline Environmental Health
Non-NASA Center

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