The insect-killing bacterium Photorhabdus luminescens has the lowest mutation rate among bacteria

Jiao Pan, Emily Williams, Way Sung, Michael Lynch, Hongan Long

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Mutation is a primary source of genetic variation that is used to power evolution. Many studies, however, have shown that most mutations are deleterious and, as a result, extremely low mutation rates might be beneficial for survival. Using a mutation accumulation experiment, an unbiased method for mutation study, we found an extremely low base-substitution mutation rate of 5.94 × 10–11 per nucleotide site per cell division (95% Poisson confidence intervals: 4.65 × 10–11, 7.48 × 10–11) and indel mutation rate of 8.25 × 10–12 per site per cell division (95% confidence intervals: 3.96 × 10–12, 1.52 × 10–11) in the bacterium Photorhabdus luminescens ATCC29999. The mutations are strongly A/T-biased with a mutation bias of 10.28 in the A/T direction. It has been hypothesized that the ability for selection to lower mutation rates is inversely proportional to the effective population size (drift-barrier hypothesis) and we found that the effective population size of this bacterium is significantly greater than most other bacteria. This finding further decreases the lower-bounds of bacterial mutation rates and provides evidence that extreme levels of replication fidelity can evolve within organisms that maintain large effective population sizes.

Original languageEnglish (US)
Pages (from-to)20-27
Number of pages8
JournalMarine Life Science and Technology
Issue number1
StatePublished - Feb 2021


  • Drift-barrier hypothesis
  • Lower-limit of mutation rate
  • Mutation accumulation
  • Mutation spectrum
  • Neutral evolution

ASJC Scopus subject areas

  • Aquatic Science
  • Biotechnology
  • Ecology, Evolution, Behavior and Systematics
  • Oceanography


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