Frequent beneficial mutations during single-colony serial transfer of streptococcus pneumoniae

Kathleen E. Stevens, Michael E. Sebert

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The appearance of new mutations within a population provides the raw material for evolution. The consistent decline in fitness observed in classical mutation accumulation studies has provided support for the long-held view that deleterious mutations are more common than beneficial mutations. Here we present results of a study using a mutation accumulation design with the bacterium Streptococcus pneumoniae in which the fitness of the derived populations increased. This rise in fitness was associated specifically with adaptation to survival during brief stationary phase periods between single-colony population bottlenecks. To understand better the population dynamics behind this unanticipated adaptation, we developed a maximum likelihood model describing the processes of mutation and stationary-phase selection in the context of frequent population bottlenecks. Using this model, we estimate that the rate of beneficial mutations may be as high as 4.8×10 -4 events per genome for each time interval corresponding to the pneumococcal generation time. This rate is several orders of magnitude higher than earlier estimates of beneficial mutation rates in bacteria but supports recent results obtained through the propagation of small populations of Escherichia coli. Our findings indicate that beneficial mutations may be relatively frequent in bacteria and suggest that in S. pneumoniae, which develops natural competence for transformation, a steady supply of such mutations may be available for sampling by recombination.

Original languageEnglish (US)
Article numbere1002232
JournalPLoS Genetics
Volume7
Issue number8
DOIs
StatePublished - Aug 2011

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Streptococcus pneumoniae
pneumonia
mutation
Mutation
Population
Mutation Rate
Bacteria
population bottleneck
fitness
bacterium
Population Dynamics
bacteria
Mental Competency
Genetic Recombination
Genome
Escherichia coli
generation time
recombination
raw materials
population dynamics

ASJC Scopus subject areas

  • Genetics
  • Molecular Biology
  • Ecology, Evolution, Behavior and Systematics
  • Cancer Research
  • Genetics(clinical)

Cite this

Frequent beneficial mutations during single-colony serial transfer of streptococcus pneumoniae. / Stevens, Kathleen E.; Sebert, Michael E.

In: PLoS Genetics, Vol. 7, No. 8, e1002232, 08.2011.

Research output: Contribution to journalArticle

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