This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by La Duc, M. T.
Right arrow Articles by Venkateswaran, K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by La Duc, M. T.
Right arrow Articles by Venkateswaran, K.
Agricola
Right arrow Articles by La Duc, M. T.
Right arrow Articles by Venkateswaran, K.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, April 2007, p. 2600-2611, Vol. 73, No. 8
0099-2240/07/$08.00+0     doi:10.1128/AEM.03007-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Isolation and Characterization of Bacteria Capable of Tolerating the Extreme Conditions of Clean Room Environments{triangledown}

Myron T. La Duc, Anne Dekas, Shariff Osman, Christine Moissl,{dagger} David Newcombe, and Kasthuri Venkateswaran*

Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California

Received 29 December 2006/ Accepted 12 February 2007

In assessing the bacterial populations present in spacecraft assembly, spacecraft test, and launch preparation facilities, extremophilic bacteria (requiring severe conditions for growth) and extremotolerant bacteria (tolerant to extreme conditions) were isolated. Several cultivation approaches were employed to select for and identify bacteria that not only survive the nutrient-limiting conditions of clean room environments but can also withstand even more inhospitable environmental stresses. Due to their proximity to spacefaring objects, these bacteria pose a considerable risk for forward contamination of extraterrestrial sites. Samples collected from four geographically distinct National Aeronautics and Space Administration clean rooms were challenged with UV-C irradiation, 5% hydrogen peroxide, heat shock, pH extremes (pH 3.0 and 11.0), temperature extremes (4°C to 65°C), and hypersalinity (25% NaCl) prior to and/or during cultivation as a means of selecting for extremotolerant bacteria. Culture-independent approaches were employed to measure viable microbial (ATP-based) and total bacterial (quantitative PCR-based) burdens. Intracellular ATP concentrations suggested a viable microbial presence ranging from below detection limits to 106 cells/m2. However, only 0.1 to 55% of these viable cells were able to grow on defined culture medium. Isolated members of the Bacillaceae family were more physiologically diverse than those reported in previous studies, including thermophiles (Geobacillus), obligate anaerobes (Paenibacillus), and halotolerant, alkalophilic species (Oceanobacillus and Exiguobacterium). Non-spore-forming microbes ({alpha}- and ß-proteobacteria and actinobacteria) exhibiting tolerance to the selected stresses were also encountered. The multiassay cultivation approach employed herein enhances the current understanding of the physiological diversity of bacteria housed in these clean rooms and leads us to ponder the origin and means of translocation of thermophiles, anaerobes, and halotolerant alkalophiles into these environments.

* Corresponding author. Mailing address: Biotechnology and Planetary Protection Group, M/S 89, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109. Phone: (818) 393-1481. Fax: (818) 393-4176. E-mail: kjvenkat{at}jpl.nasa.gov

{triangledown} Published ahead of print on 16 February 2007.

{dagger} Present address: Lehrstuhl fuer Mikrobiologie und Archaeenzentrum, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg, Germany.

Applied and Environmental Microbiology, April 2007, p. 2600-2611, Vol. 73, No. 8
0099-2240/07/$08.00+0     doi:10.1128/AEM.03007-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Stieglmeier, M., Wirth, R., Kminek, G., Moissl-Eichinger, C. (2009). Cultivation of Anaerobic and Facultatively Anaerobic Bacteria from Spacecraft-Associated Clean Rooms. Appl. Environ. Microbiol. 75: 3484-3491 [Abstract] [Full Text]  
  • Vaishampayan, P., Miyashita, M., Ohnishi, A., Satomi, M., Rooney, A., La Duc, M. T., Venkateswaran, K. (2009). Description of Rummeliibacillus stabekisii gen. nov., sp. nov. and reclassification of Bacillus pycnus Nakamura et al. 2002 as Rummeliibacillus pycnus comb. nov.. Int. J. Syst. Evol. Microbiol. 59: 1094-1099 [Abstract] [Full Text]  
  • Behrendt, U., Schumann, P., Ulrich, A. (2008). Agrococcus versicolor sp. nov., an actinobacterium associated with the phyllosphere of potato plants. Int. J. Syst. Evol. Microbiol. 58: 2833-2838 [Abstract] [Full Text]  
  • Osman, S., Peeters, Z., La Duc, M. T., Mancinelli, R., Ehrenfreund, P., Venkateswaran, K. (2008). Effect of Shadowing on Survival of Bacteria under Conditions Simulating the Martian Atmosphere and UV Radiation. Appl. Environ. Microbiol. 74: 959-970 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»