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Directed evolution of cell size in Escherichia coli
Mari Yoshida1, Saburo Tsuru2, Naoko Hirata3
1Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan. maaaaaari8852@gmail.com.
BMC Evolutionary Biology
|December 18, 2014
Summary
Bacterial cell size can evolve rapidly through a few genetic mutations without impacting growth rate. This evolution allows bacteria to adapt diverse cell sizes for survival strategies, demonstrating evolutionary flexibility.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genetics
Background:
- Bacterial cell size is intrinsically linked to critical processes like DNA replication, cell division, and growth rate.
- Cell size can be a target for evolutionary adaptation, potentially for predator evasion.
- A key question is whether bacterial cell size can evolve without negatively affecting growth.
Purpose of the Study:
- To investigate if bacterial cell size can evolve without incurring a growth burden.
- To determine the genetic basis and speed of cell size evolution in bacteria.
Main Methods:
- Directed evolution was used with a laboratory strain of Escherichia coli.
- A cell sorter was employed to isolate cells within specific size ranges for culturing.
- Whole genome sequencing was performed to identify mutations responsible for observed size changes.
Main Results:
- Significant alterations in bacterial cell size were achieved within 400 generations.
- The width of the cell size distribution was also modified.
- These evolutionary changes in cell size occurred without any detectable reduction in growth rate.
- Mutations in genes associated with membrane synthesis were identified as key drivers of size evolution.
Conclusions:
- Bacterial cell size evolution is achievable through a limited number of mutations.
- This evolution can occur independently of growth rate reduction.
- The findings suggest rapid evolutionary adaptation of cell size is possible, supporting diverse bacterial survival strategies.
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