Related Experiment Video
Updated: Jan 14, 2026
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Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach
Published on: December 14, 2019
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Non-conjugative plasmids limit their mobility to persist in nature
Akshay Sabnis1, Wendy Figueroa1, Alfonso Santos-López2
1Department of Infectious Disease, Imperial College London, London SW7 2AZ, UK; Centre for Bacterial Resistance Biology, Imperial College London, London SW7 2AZ, UK.
Cell Reports
|October 23, 2025
Summary
Plasmids evolve to limit their own spread, maintaining diversity to protect bacteria from threats like antibiotics and phages. This strategy ensures long-term survival, explaining low plasmid mobility in nature.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genetics
Background:
- Plasmids are mobile genetic elements that spread beneficial genes, including antibiotic resistance.
- The evolutionary drivers of plasmid distribution and mobility are not fully understood.
- Non-conjugative plasmids are thought to spread efficiently, but evidence is limited.
Purpose of the Study:
- To investigate the evolutionary strategies of non-conjugative plasmids in Staphylococcus aureus.
- To challenge the hypothesis that non-conjugative plasmids evolved for high-frequency spread.
- To understand the role of plasmid mobility in bacterial population dynamics and survival.
Main Methods:
- Comparative genomic analysis of Staphylococcus aureus plasmids.
- Investigating the presence/absence of phage-related DNA sequences (pac/cos sites).
- Modeling plasmid transfer dynamics in mixed bacterial populations.
Main Results:
- Staphylococcus aureus non-conjugative plasmids lack essential phage-mediated transduction sites (pac/cos).
- Acquiring phage DNA to enhance mobility is detrimental to plasmid evolution.
- Low plasmid transfer rates promote plasmid coexistence and maintain bacterial protection.
- High plasmid mobility reduces plasmid diversity, diminishing protective benefits and increasing population vulnerability.
Conclusions:
- Plasmids evolve to restrict their own mobility, prioritizing diversity maintenance over rapid spread.
- This restricted mobility ensures the long-term survival of bacterial populations against environmental threats.
- The findings explain the observed low mobility of plasmids in natural environments.
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