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Stochastic processes influence stationary-phase decisions in Bacillus subtilis.
Heather Maughan1, Wayne L Nicholson
1Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
Journal of Bacteriology
|March 19, 2004
Summary
Phenotypic variation in bacterial populations may stem from random molecular fluctuations, or "noise." This study found that Bacillus subtilis did not improve sporulation efficiency under selection, suggesting this noise is independent of genotype.
Area of Science:
- Microbiology
- Genetics
- Evolutionary Biology
Background:
- Phenotypic variation in clonal bacterial populations is proposed to arise from intracellular noise.
- This intracellular noise, random fluctuations in cellular molecules, is predicted to be unaffected by selective pressures.
Purpose of the Study:
- To investigate the role of intracellular noise in bacterial phenotypic variation.
- To determine if selection pressure can alter sporulation efficiency in Bacillus subtilis populations.
Main Methods:
- Propagated five Bacillus subtilis populations for 5,000 generations.
- Applied selection pressure for the sporulation phenotype.
Main Results:
- None of the five Bacillus subtilis populations showed improved sporulation efficiency despite selection.
- The lack of response to selection indicates that intracellular noise is independent of heritable genotype.
Conclusions:
- Intracellular noise is a significant factor in bacterial phenotypic variation.
- This noise is independent of heritable genotype and not subject to selective pressure for the sporulation phenotype.