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A New Method for Estimating Bacterial Abundances in Natural Samples using SublimationWe have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert were heated to a temperature of 500 C for several seconds under reduced pressure. The sublimate was collected on a cold finger and the amount of adenine released from the samples then determined by high performance liquid chromatography (HPLC) with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from approx. l0(exp 5) to l0(exp 9) E. coli cell equivalents per gram. For most of these samples, the sublimation based cell counts were in agreement with total bacterial counts obtained by traditional DAPI staining. The simplicity and robustness of the sublimation technique compared to the DAPI staining method makes this approach particularly attractive for use by spacecraft instrumentation. NASA is currently planning to send a lander to Mars in 2009 in order to assess whether or not organic compounds, especially those that might be associated with life, are present in Martian surface samples. Based on our analyses of the Atacama Desert soil samples, several million bacterial cells per gam of Martian soil should be detectable using this sublimation technique.
Document ID
20040082181
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Glavin, Daniel P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Cleaves, H. James (Scripps Institution of Oceanography La Jolla, CA, United States)
Schubert, Michael (Centre National de la Recherche Scientifique Lyon, France)
Aubrey, Andrew (Scripps Institution of Oceanography La Jolla, CA, United States)
Bada, Jeffrey L. (Scripps Institution of Oceanography La Jolla, CA, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2004
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Public Use Permitted.

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