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7335770 
Book/Book Chapter 
Space Microbiology: Planetary Protection, Burden, Diversity and Significance of Spacecraft Associated Microbes 
Bruckner, J; Osman, S; Venkateswaran, K; Conley, C 
2009 
Elsevier Inc. 
Encyclopedia of Microbiology 
52-65 
English 
A driving force behind space exploration is the search for extraterrestrial life and/or environmental conditions that may give rise to or support it. To prevent forward contamination and maintain the scientific integrity of future life-detection missions it is important to characterize and attempt to eliminate terrestrial microorganisms associated with exploratory spacecraft and landing vehicles. In accordance with regulations outlined in international treaties, NASA utilizes a traditional, cultivation-based assay to assess spacecraft cleanliness. Although a valid proxy for bacterial abundance, this single assay offers only a limited assessment of the microbial community present. Molecular methods are generally not nearly as sensitive as culture-based ones - it's extremely challenging to detect a single organism using molecular methods, but culture-based methods do this routinely. These modern techniques have demonstrated that low levels of biological burden exist on spacecraft and within spacecraft assembly facilities. While traditional culture-dependent assays have suggested these environments harbor mainly Gram-positive spore-forming species, molecular assays revealed a substantially more diverse microbial community. Clearly, the benefits of modern molecular techniques and the need to obtain isolates for physiology and resistance studies illustrate the importance of using a variety of diverse assays to study spacecraft-associated habitats. As such, NASA utilizes and is continuing to develop protocols using both molecular and culture-based assays to enable future life-detection missions. © 2009 Elsevier Inc. All rights reserved. 
16S rRNA gene sequencing; Archaea; Archiving; Bacteria; Clean room; Cultivation; Microbes; Molecular community analysis; Planetary protection; Policy implementation; Spacecraft assembly facility; Spores