HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary Material Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Ihssen, J. Articles by Egli, T. Search for Related Content PubMed PubMed Citation Articles by Ihssen, J. Articles by Egli, T. Agricola Articles by Ihssen, J. Articles by Egli, T.

Comparative genomic hybridization and physiological characterization of environmental isolates indicate that significant (eco-)physiological properties are highly conserved in the species Escherichia coli

¹ Swiss Federal Institute for Environmental Science and Technology, PO Box 611, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland
² Empa, Swiss Federal Institute for Materials Testing and Technology, Lerchenfeldstrasse 5, CH-9014 St Gallen, Switzerland
³ Istituto Cantonale di Microbiologia, Via Mirasole 22A, CH-6500 Bellinzona, Switzerland
⁴ Department of Biology, University of Genova, Corso Europa 26 V piano, 16132 Genova, Italy
⁵ Genomic Research Laboratory, University Hospitals of Geneva, rue Micheli-du-Crest 24, CH-1211 Geneva 14, Switzerland
⁶ VIDO – Vaccine & Infectious Diseases Organization, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada

Correspondence
Thomas Egli
egli{at}eawag.ch

Escherichia coli, the common inhabitant of the mammalian intestine, exhibits considerable intraspecies genomic variation, which has been suggested to reflect adaptation to different ecological niches. Also, regulatory trade-offs, e.g. between catabolic versatility and stress protection, are thought to result in significant physiological differences between strains. For these reasons, the relevance of experimental observations made for ‘domesticated’ E. coli strains with regard to the behaviour of this species in its natural environments is often questioned and doubts are frequently raised on the status of E. coli as a defined species. The variability of important (eco-)physiological functions, such as carbon substrate uptake and breakdown capabilities, as well as stress defence mechanisms, in the genomes of commensal and pathogenic E. coli strains were therefore investigated. Furthermore, (eco-)physiological properties of environmental strains were compared to standard laboratory strain K-12 MG1655. Catabolic, stress protection, and carbon- and energy source transport operons showed a very low intraspecies variability in 57 commensal and pathogenic E. coli. Environmental isolates adapted to glucose-limited growth in a similar way as E. coli MG1655, namely by increasing their catabolic flexibility and by inducing high-affinity substrate uptake systems. The results obtained indicate that significant (eco-)physiological properties are highly conserved in the natural population of E. coli. This questions the proposed dominant role of horizontal gene transfer for niche adaptation.

Microarray data, design and oligonucleotide sequences GEO DataSets accession nos are GSE6407, GSE6486 and GPL4618.

The raw DNA microarray data of this and other studies and the genomic DNA labelling protocol are available with the online version of this paper.