[Impact of mutation rate on the adaptation of gut bacteria].
To study the role of mutator bacteria in the evolution of bacterial populations, we followed the impact of the mutation rate of Escherichia coli strains in the colonisation of the gut of axenic mice and the evolution of the mutation rate of bacterial populations living in the gut. We show that mutator bacteria have an advantage during the colonization. This adaptive advantage comes from their ability to generate adaptive mutations faster than wild type strains, mutations that allow their maintenance in the ecosystem. However, while mutator bacteria are becoming specialised to the environment they are living in, they accumulate mutations that may be deleterious or lethal in secondary environments. By following the evolution of the mutation rate of bacterial populations living in the gut of mice receiving antibiotics, we show that this therapy selects not only for antibiotic resistant mutants but also for mutator alleles that enhance mutation rates and are responsible for the appearance of the resistance. The costs of a high mutation rate, due to the accumulation of mutations, is seen in environments where changes are recurrent. In an ever-changing situation where every change is new, mutator bacteria might help the evolution of bacterial populations.
Génétique Moléculaire Evolutive et Médicale, INSERM U571, Faculté de Médecine Necker-Enfants Malades, 156, rue de Vaugirard, 75730 Paris Cedex 15, France.
Antoine
A
Giraud
Michel
M
Fons
François
F
Taddei
D000222:Adaptation, Physiological; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000502:physiology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029968:Escherichia coli Proteins; D019143:Evolution, Molecular; D005856:Germ-Free Life; D007422:Intestines / Q000382:microbiology*; D051379:Mice; D051719:MutS DNA Mismatch-Binding Protein; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics / Q000502:physiology
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D000251:Adenosine Triphosphatases; D051719:MutS DNA Mismatch-Binding Protein; C497175:MutS protein, E coli