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Memory and fitness optimization of bacteria under fluctuating environments
Guillaume Lambert1, Edo Kussell, Edo Kussel2
1The Institute of Genomics and Systems Biology, The University of Chicago, Chicago, Illinois, United States of America.
Plos Genetics
|September 26, 2014
Summary
Bacteria use non-genetic memory to survive fluctuating environments. This memory, via stable proteins or gene expression hysteresis, improves adaptation and long-term fitness in changing conditions.
Area of Science:
- Microbiology
- Systems Biology
- Evolutionary Biology
Background:
- Bacteria dynamically regulate gene expression based on nutrient availability.
- Mechanisms for transmitting adaptive phenotypic states across generations in fluctuating environments remain unclear.
Purpose of the Study:
- To investigate non-genetic memory mechanisms in Escherichia coli under fluctuating carbon sources.
- To analyze the benefits of different memory types for bacterial adaptation and fitness.
Main Methods:
- Utilized microfluidics to expose Escherichia coli to cyclical fluctuations of glucose and lactose.
- Identified and characterized two distinct types of non-genetic memory: phenotypic and response memory.
- Employed mathematical modeling to assess the impact of memory on fitness across various environmental timescales.
Main Results:
- Phenotypic memory, through stable intracellular proteins, significantly reduces lag phases during intermediate timescale fluctuations (1-10 generations).
- Response memory, a hysteretic gene expression phenomenon, enhances adaptation during short timescale fluctuations (< 1 generation).
- Mathematical models confirm that memory mechanisms confer survival advantages and improve long-term fitness in fluctuating environments.
Conclusions:
- Non-genetic memory represents a crucial survival strategy for bacteria in dynamic environments.
- These memory mechanisms are vital for adaptation to fluctuating nutrient levels, antibiotic presence, and other environmental stresses.
- Understanding these strategies provides insights into microbial adaptation and resilience.
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