Opposing effects of final population density and stress on Escherichia coli mutation rate

Rok Krašovec, Huw Richards, Danna R Gifford, Roman V. Belavkin, Alastair Channon, Elizabeth Aston, Andrew Mcbain, Christopher Knight

Research output: Contribution to journalArticlepeer-review


Evolution depends on mutations. For an individual genotype, the rate at which mutations arise is known to increase with various stressors (stress-induced mutagenesis—SIM) and decrease at high final population density (density-associated mutation-rate plasticity—DAMP). We hypothesised that these two forms of mutation-rate plasticity would have opposing effects across a nutrient gradient. Here we test this hypothesis, culturing Escherichia coli in increasingly rich media. We distinguish an increase in mutation rate with added nutrients through SIM (dependent on error-prone polymerases Pol IV and Pol V) and an opposing effect of DAMP (dependent on MutT, which removes oxidised G nucleotides). The combination of DAMP and SIM results in a mutation rate minimum at intermediate nutrient levels (which can support 7 × 108 cells ml−1). These findings demonstrate a strikingly close and nuanced relationship of ecological factors—stress and population density—with mutation, the fuel of all evolution.
Original languageEnglish
Pages (from-to)2981-2987
JournalISME Journal
Early online date7 Aug 2018
Publication statusPublished - 2018


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