Mutation Dynamics in Bacterial Evolution

Mutation dynamics in bacterial populations underpin the generation of genetic diversity that drives adaptation, speciation and the emergence of antimicrobial resistance. Spontaneous base substitutions, insertions, deletions and chromosomal rearrangements arise from intrinsic errors in DNA replication and repair, while extrinsic factors such as ultraviolet light, oxidative stress and chemical agents further modulate both the rate and spectrum of mutations. Far from being a fixed property, the mutation rate can fluctuate in response to environmental cues or social interactions, enabling bacteria to balance genomic stability with the potential for rapid adaptation. Hypermutator lineages, often deficient in mismatch repair or proofreading functions, can sweep through populations under shifting selective pressures but may revert to lower-rate states once stress subsides, reflecting an evolutionary trade-off between evolvability and mutational load. Non-genetic inheritance of mutation-rate phenotypes, mediated by protein expression noise or epigenetic marks, has emerged as an additional layer of regulation. These combined mechanisms shape the availability of adaptive variants in diverse habitats from soils and aquatic ecosystems to the human microbiota and clinical settings. Understanding these processes is essential to predict bacterial evolutionary trajectories and to develop strategies that limit the rise of drug resistance.

Research from Nature Portfolio

Studies of extrinsic mutagenic inputs have revealed that periodic ultraviolet exposure can drive mutation accumulation at rates exceeding those of classical mutator strains, broadening the mutational spectrum and challenging the fidelity of DNA repair systems. The resulting high upper limit of mutation frequencies underscores the pervasive influence of environmental mutagens on evolution. In parallel, investigations into social control of mutagenesis have demonstrated that mutation-rate plasticity to rifampicin resistance is inversely related to population density. This plasticity requires a quorum-sensing component that links cell–cell interactions to the regulation of DNA methylation cycles, indicating that bacterial communities can modulate their collective mutation supply through genetic switches responsive to social cues.

Research from all publishers

Recent work has shown that collective detoxification of hydrogen peroxide in dense bacterial populations underlies a negative relationship between cell density and mutation rate, providing a mechanistic explanation for community-shaped mutation-rate plasticity. Another line of research has focused on phenotype switching of the mutation rate, demonstrating that epigenetic inheritance of DNA repair protein expression noise can transiently generate mutator and anti-mutator phenotypes, thereby accelerating adaptation on complex fitness landscapes. Finally, investigations into antibiotic combination therapies have highlighted that mutator alleles can drive the evolution of multi-resistance even under dosing regimes designed to prevent sequential resistance mutations. By hitchhiking with initial resistance mutations, hypermutators facilitate the acquisition of additional drug-specific alleles, raising concerns about the efficacy of combination treatments in the presence of elevated mutation rates.

Mutation Dynamics in Bacterial Evolution publication trend

The graph below shows the total number of articles in mutation dynamics in bacterial evolution across all publications each year (not limited to Nature Index journals).

Technical terms

Mutation rate plasticity: Environment- or context-dependent variation in the frequency of spontaneous genetic changes.

Hypermutator: Bacterial strain with a markedly elevated mutation rate, often due to defects in DNA repair pathways.

Quorum sensing: Mechanism by which bacterial cells detect population density and coordinate gene expression.

Non-genetic inheritance: Transmission of phenotypic traits through means other than changes in DNA sequence, such as protein expression noise or epigenetic modifications.

References

1. Mutation accumulation under UV radiation in Escherichia coli. Scientific Reports (2017).
2. Mutation rate plasticity in rifampicin resistance depends on Escherichia coli cell–cell interactions. Nature Communications (2014).
3. Collective peroxide detoxification determines microbial mutation rate plasticity in E. coli. PLOS Biology (2024).
4. Phenotype switching of the mutation rate facilitates adaptive evolution. Genetics (2023).
5. Mutators can drive the evolution of multi-resistance to antibiotics. PLOS Genetics (2023).