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 Berney, M.
Right arrow Articles by Egli, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Berney, M.
Right arrow Articles by Egli, T.
Agricola
Right arrow Articles by Berney, M.
Right arrow Articles by Egli, T.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, April 2006, p. 2586-2593, Vol. 72, No. 4
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.4.2586-2593.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Specific Growth Rate Determines the Sensitivity of Escherichia coli to Thermal, UVA, and Solar Disinfection

Michael Berney, Hans-Ulrich Weilenmann, Julian Ihssen, Claudio Bassin, and Thomas Egli*

Swiss Federal Institute of Aquatic Science and Technology (Eawag), Überlandstrasse 133, P.O. Box 611, CH-8600 Dübendorf, Switzerland

Received 30 August 2005/ Accepted 20 January 2006

Knowledge about the sensitivity of the test organism is essential for the evaluation of any disinfection method. In this work we show that sensitivity of Escherichia coli MG1655 to three physical stresses (mild heat, UVA light, and sunlight) that are relevant in the disinfection of drinking water with solar radiation is determined by the specific growth rate of the culture. Batch- and chemostat-cultivated cells from cultures with similar specific growth rates showed similar stress sensitivities. Generally, fast-growing cells were more sensitive to the stresses than slow-growing cells. For example, slow-growing chemostat-cultivated cells (D = 0.08 h–1) and stationary-phase bacteria from batch culture that were exposed to mild heat had very similar T90 (time until 90% of the population is inactivated) values (T90, chemostat = 2.66 h; T90, batch = 2.62 h), whereas T90 for cells growing at a µ of 0.9 h–1 was 0.2 h. We present evidence that the stress sensitivity of E. coli is correlated with the intracellular level of the alternative sigma factor RpoS. This is also supported by the fact that E. coli rpoS mutant cells were more stress sensitive than the parent strain by factors of 4.9 (mild heat), 5.3 (UVA light), and 4.1 (sunlight). Furthermore, modeling of inactivation curves with GInaFiT revealed that the shape of inactivation curves changed depending on the specific growth rate. Inactivation curves of cells from fast-growing cultures (µ = 1.0 h–1) that were irradiated with UVA light showed a tailing effect, while for slow-growing cultures (µ = 0.3 h–1), inactivation curves with shoulders were obtained. Our findings emphasize the need for accurate reporting of specific growth rates and detailed culture conditions in disinfection studies to allow comparison of data from different studies and laboratories and sound interpretation of the data obtained.

* Corresponding author. Mailing address: Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, P.O. Box 611, CH-8600 Dübendorf, Switzerland. Phone: 41 44 823 5158. Fax: 41 44 823 5547. E-mail: egli{at}eawag.ch.

Applied and Environmental Microbiology, April 2006, p. 2586-2593, Vol. 72, No. 4
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.4.2586-2593.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Bosshard, F., Berney, M., Scheifele, M., Weilenmann, H.-U., Egli, T. (2009). Solar disinfection (SODIS) and subsequent dark storage of Salmonella typhimurium and Shigella flexneri monitored by flow cytometry. Microbiology 155: 1310-1317 [Abstract] [Full Text]  
  • Kajfasz, J. K., Martinez, A. R., Rivera-Ramos, I., Abranches, J., Koo, H., Quivey, R. G. Jr., Lemos, J. A. (2009). Role of Clp Proteins in Expression of Virulence Properties of Streptococcus mutans. J. Bacteriol. 191: 2060-2068 [Abstract] [Full Text]  
  • Zabala, B., Garcia, K., Espejo, R. T. (2009). Enhancement of UV Light Sensitivity of a Vibrio parahaemolyticus O3:K6 Pandemic Strain Due to Natural Lysogenization by a Telomeric Phage. Appl. Environ. Microbiol. 75: 1697-1702 [Abstract] [Full Text]  
  • White-Ziegler, C. A., Um, S., Perez, N. M., Berns, A. L., Malhowski, A. J., Young, S. (2008). Low temperature (23 {degrees}C) increases expression of biofilm-, cold-shock- and RpoS-dependent genes in Escherichia coli K-12. Microbiology 154: 148-166 [Abstract] [Full Text]  
  • Berney, M., Hammes, F., Bosshard, F., Weilenmann, H.-U., Egli, T. (2007). Assessment and Interpretation of Bacterial Viability by Using the LIVE/DEAD BacLight Kit in Combination with Flow Cytometry. Appl. Environ. Microbiol. 73: 3283-3290 [Abstract] [Full Text]  
  • Lemos, J. A., Luzardo, Y., Burne, R. A. (2007). Physiologic Effects of Forced Down-Regulation of dnaK and groEL Expression in Streptococcus mutans. J. Bacteriol. 189: 1582-1588 [Abstract] [Full Text]  
  • Berney, M., Weilenmann, H.-U., Egli, T. (2006). Flow-cytometric study of vital cellular functions in Escherichia coli during solar disinfection (SODIS). Microbiology 152: 1719-1729 [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»