Frequent Beneficial Mutations during Single-Colony Serial Transfer of Streptococcus pneumoniae

• DOI: 10.1371/journal.pgen.1002232
• Publication Date: 2011-08-18T19:00:12Z
• Authors: Kathleen E. Stevens; Michael E. Sebert
• Keywords: Mutation Accumulation

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