Molecular characterization of commensal Escherichia coli adapted to different compartments of the porcine gastrointestinal tract

Sam Abraham, David M. Gordon, James Chin, Huub J. M. Brouwers, Peter Njuguna, Mitchell D. Groves, Ren Zhang, Toni A. Chapman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

The role of Escherichia coli as a pathogen has been the focus of considerable study, while much less is known about it as a commensal and how it adapts to and colonizes different environmental niches within the mammalian gut. In this study, we characterize Escherichia coli organisms (n = 146) isolated from different regions of the intestinal tracts of eight pigs (dueodenum, ileum, colon, and feces). The isolates were typed using the method of random amplified polymorphic DNA (RAPD) and screened for the presence of bacteriocin genes and plasmid replicon types. Molecular analysis of variance using the RAPD data showed that E. coli isolates are nonrandomly distributed among different gut regions, and that gut region accounted for 25% (P <0.001) of the observed variation among strains. Bacteriocin screening revealed that a bacteriocin gene was detected in 45% of the isolates, with 43% carrying colicin genes and 3% carrying microcin genes. Of the bacteriocins observed (H47, E3, E1, E2, E7, Ia/Ib, and B/M), the frequency with which they were detected varied with respect to gut region for the colicins E2, E7, Ia/Ib, and B/M. The plasmid replicon typing gave rise to 25 profiles from the 13 Inc types detected. Inc F types were detected most frequently, followed by Inc HI1 and N types. Of the Inc types detected, 7 were nonrandomly distributed among isolates from the different regions of the gut. The results of this study indicate that not only may the different regions of the gastrointestinal tract harbor different strains of E. coli but also that strains from different regions have different characteristics.

Original languageEnglish
Pages (from-to)6799-6803
Number of pages5
JournalApplied and Environmental Microbiology
Volume78
Issue number19
DOIs
Publication statusPublished - Oct 2012
Externally publishedYes

Keywords

  • PLASMIDS
  • EVOLUTION
  • STRAINS
  • BACTERIOCINS
  • COLICINOGENY
  • POLYMORPHISM
  • FREQUENCY
  • DYNAMICS
  • HOST
  • GENE

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