ATP as a biomarker of viable microorganisms in clean-room facilities

• Published in: Journal of microbiological methods Vol. 52; no. 3; pp. 367 - 377
• Main Authors: Venkateswaran, Kasthuri, Hattori, Noriaki, La Duc, Myron T, Kern, Roger
• Format: Journal Article
• Language: English
• Published: Legacy CDMS Elsevier B.V 01-03-2003; Elsevier Science
• Subjects: 16S rDNA; Adenosine Triphosphate - analysis; ATP; Bacteria - growth & development; Bacteria - isolation & purification; Biological and medical sciences; Biomarkers - analysis; Clean-rooms; Cloning, Molecular - methods; Colony Count, Microbial - methods; Culture Media - chemistry; DNA, Bacterial - isolation & purification; Environment, Controlled; Fundamental and applied biological sciences. Psychology; Life Sciences (General); Microbial detection; Microbiological Techniques - methods; Microbiology; Miscellaneous; Space life sciences; Spacecraft; Viable but noncultivable; Microbial detection; 16S rDNA; ATP; Viable but noncultivable; Clean-rooms; Nasa Discipline Environmental Health; Non-Nasa Center; Enzyme; Luciferase; Ribosomal DNA; Luminescence; Spacecraft; Biological marker; Clean room; Oxidoreductases; Microorganism; Measurement method; Detection; Biological contamination; NASA Discipline Environmental Health; Non-NASA Center
• ISSN: 0167-7012; 1872-8359
• DOI: 10.1016/S0167-7012(02)00192-6

A 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 μm, 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.