Journal Article

The Evolution of Reduced Microbial Killing

Jan A. C. Vriezen, Michael Valliere and Margaret A. Riley

in Genome Biology and Evolution

Published on behalf of Society for Molecular Biology and Evolution

Volume 1, issue , pages 400-408
Published in print January 2009 |
Published online October 2009 | e-ISSN: 1759-6653 | DOI:

More Like This

Show all results sharing these subjects:

  • Bioinformatics and Computational Biology
  • Evolutionary Biology
  • Genetics and Genomics


Show Summary Details


Bacteria engage in a never-ending arms race in which they compete for limited resources and niche space. The outcome of this intense interaction is the evolution of a powerful arsenal of biological weapons. Perhaps the most studied of these are colicins, plasmid-based toxins produced by and active against Escherichia coli. The present study was designed to explore the molecular responses of a colicin-producing strain during serial transfer evolution. What evolutionary changes occur when colicins are produced with no target present? Can killing ability be maintained in the absence of a target? To address these, and other, questions, colicinogenic strains and a noncolicinogenic ancestor were evolved for 253 generations. Samples were taken throughout the experiment and tested for killing ability. By the 38th transfer, a decreased killing ability and an increase in fitness were observed in the colicin-producing strains. Surprisingly, DNA sequence determination of the colicin plasmids revealed no changes in plasmid sequences. However, a set of chromosomally encoded loci experienced changes in gene expression that were positively associated with the reduction in killing. The most significant expression changes were observed in DNA repair genes (which were downregulated in the evolved strains), Mg ion uptake genes (which were upregulated), and late prophage genes (which were upregulated). These results indicate a fine-tuned response to the evolutionary pressures of colicin production, with far more genes involved than had been anticipated.

Keywords: Escherichia coli; serial transfer; colicinogeny; transcriptional profiling; prophage; DNA repair

Journal Article.  6952 words.  Illustrated.

Subjects: Bioinformatics and Computational Biology ; Evolutionary Biology ; Genetics and Genomics

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.