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Standardization of spore inactivation method for PMA-PhyloChip analysis

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dc.contributor.author Schrader, Michael
dc.date.accessioned 2013-08-20T14:40:53Z
dc.date.available 2013-08-20T14:40:53Z
dc.date.issued 2011-08
dc.identifier.citation USRP - NASA Undergraduate Student Research Program. Pasadena, California, August 2011 en_US
dc.identifier.clearanceno 11-4545
dc.identifier.uri http://hdl.handle.net/2014/43574
dc.description.abstract In compliance with the Committee on Space Research (COSPAR) planetary protection policy, National Aeronautics and Space Administration (NASA) monitors the total microbial burden of spacecraft as a means for minimizing the inadvertent transfer of viable contaminant microorganisms to extraterrestrial environments (forward contamination). NASA standard assay-based counts are used both as a proxy for relative surface cleanliness and to estimate overall microbial burden as well as to assess whether forward planetary protection risk criteria are met for a given mission, which vary by the planetary body to be explored and whether or not life detection missions are present. Despite efforts to reduce presence of microorganisms from spacecraft prior to launch, microbes have been isolated from spacecraft and associated surfaces within the extreme conditions of clean room facilities (La Duc et al. 2004) using state of the art molecular technologies. Development of a more sensitive method that will better enumerate all viable microorganisms from spacecraft and associated surfaces could support future life detection missions. Current culture-based (NASA standard spore assay) and nucleic-acid-based polymerase chain reaction (PCR) methods have significant shortcomings in this type of analysis. The overall goal of this project is to evaluate and validate a new molecular method based on the use of a deoxyribonucleic acid (DNA) intercalating agent propidium monoazide (PMA). This is used in combination with DNA microarray (PhyloChip) which has been shown to identify very low levels of organisms on spacecraft associated surfaces. PMA can only penetrate the membrane of dead cells. Once penetrated, it intercalates the DNA and, upon photolysis using visible light it produces stable DNA monoadducts. This allows DNA to be unavailable for further PCR analysis. The specific aim of this study is to standardize the spore inactivation method for PMA-PhyloChip analysis. We have used the bacterial spores Bacillus subtilis 168 (standard laboratory isolate) as a test organism. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2011. en_US
dc.subject spore inactivation en_US
dc.subject spore forming bacteria en_US
dc.subject EMA-PCR methodology en_US
dc.subject planetary protection en_US
dc.title Standardization of spore inactivation method for PMA-PhyloChip analysis en_US
dc.type Other en_US


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