AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
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 Ishii, S.
Right arrow Articles by Sadowsky, M. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ishii, S.
Right arrow Articles by Sadowsky, M. J.
Agricola
Right arrow Articles by Ishii, S.
Right arrow Articles by Sadowsky, M. J.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, January 2006, p. 612-621, Vol. 72, No. 1
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.1.612-621.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Presence and Growth of Naturalized Escherichia coli in Temperate Soils from Lake Superior Watersheds

Satoshi Ishii,1 Winfried B. Ksoll,3 Randall E. Hicks,3 and Michael J. Sadowsky1,2*

Department of Soil, Water and Climate,1 BioTechnology Institute, University of Minnesota, St. Paul, Minnesota,2 Department of Biology, University of Minnesota—Duluth, Duluth, Minnesota3

Received 18 August 2005/ Accepted 26 October 2005

The presence of Escherichia coli in water is used as an indicator of fecal contamination, but recent reports indicate that soil populations can also be detected in tropical, subtropical, and some temperate environments. In this study, we report that viable E. coli populations were repeatedly isolated from northern temperate soils in three Lake Superior watersheds from October 2003 to October 2004. Seasonal variation in the population density of soilborne E. coli was observed; the greatest cell densities, up to 3 x 103 CFU/g soil, were found in the summer to fall (June to October), and the lowest numbers, ≤1 CFU/g soil, occurred during the winter to spring months (February to May). Horizontal, fluorophore-enhanced repetitive extragenic palindromic PCR (HFERP) DNA fingerprint analyses indicated that identical soilborne E. coli genotypes, those with ≥92% similarity values, overwintered in frozen soil and were present over time. Soilborne E. coli strains had HFERP DNA fingerprints that were unique to specific soils and locations, suggesting that these E. coli strains became naturalized, autochthonous members of the soil microbial community. In laboratory studies, naturalized E. coli strains had the ability to grow and replicate to high cell densities, up to 4.2 x 105 CFU/g soil, in nonsterile soils when incubated at 30 or 37°C and survived longer than 1 month when soil temperatures were ≤25°C. To our knowledge, this is the first report of the growth of naturalized E. coli in nonsterile, nonamended soils. The presence of significant populations of naturalized populations of E. coli in temperate soils may confound the use of this bacterium as an indicator of fecal contamination.

* Corresponding author. Mailing address: University of Minnesota, Department of Soil, Water, and Climate, 1991 Upper Buford Circle, 439 Borlaug Hall, St. Paul, MN 55108. Phone: (612) 624-2706. Fax: (612) 625-2208. E-mail: Sadowsky{at}umn.edu

Applied and Environmental Microbiology, January 2006, p. 612-621, Vol. 72, No. 1
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.1.612-621.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 2006 by the American Society for Microbiology. All rights reserved.