The influence of cellular physiology on the initiation of mutational pathways in Escherichia coli populations

Lucinda Notley-McRobb, Shona Seeto, Thomas Ferenci*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)

Abstract

The factors affecting the direction of evolutionary pathways and the reproducibility of adaptive responses were investigated under closely related but non-identical conditions. Replicate chemostat cultures of Escherichia coli were compared when adapting to partial or severe glucose limitation. Four independent populations used a reproducible sequence of early mutational changes under both conditions, with rpoS mutations always occurring first before mgl. However, there were interesting differences in the timing of mutational sweeps: rpoS mutations appeared in a clock-like fashion under both partial and severe glucose limitation, while mgl sweeps arose under both conditions but at different times. Interestingly, malT and mlc mutations appeared only under severe limitation. Even though the ancestors were genotypically identical, the semi-differentiated properties of bacteria growing with mild or severe glucose limitation sent the populations in characteristic directions. Mutation supply and the fitness contribution of mutations were estimated and demonstrated to be potential influences in the choice of particular adaptation pathways under severe and mild glucose limitation. Predicting all the mutations fixed in adapting populations is beyond our current understanding of evolutionary processes, but the interplay between ancestor physiology and the initiation of adaptation pathways is demonstrated and definable in bacterial populations.

Original languageEnglish
Pages (from-to)843-848
Number of pages6
JournalProceedings of the Royal Society B: Biological Sciences
Volume270
Issue number1517
Publication statusPublished - 22 Apr 2003
Externally publishedYes

Keywords

  • Chemostat populations
  • Glucose limitation
  • Glucose transporters
  • Hunger response
  • Mutation rates
  • Mutational sweeps

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