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Updated: May 11, 2026
13:19
The Use of Chemostats in Microbial Systems Biology
Published on: October 14, 2013
30.9K
Physiology, fast and slow: bacterial response to variable resource stoichiometry and dilution rate
Logan M Peoples1, Jana Isanta-Navarro1,2, Benedicta Bras1
1Flathead Lake Biological Station, University of Montana, Polson, Montana, USA.
Msystems
|July 9, 2024
Summary
Bacteria like Pseudomonas putida dynamically adjust their physiology to survive nutrient and energy limitations. They change elemental composition and gene expression, forming aggregates at faster growth rates to maintain favorable conditions.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Microorganisms adapt to nutrient and energy limitations for survival and reproduction.
- Understanding these adaptations is key to microbial ecology and evolutionary fitness.
- Pseudomonas putida serves as a model organism to study bacterial responses to resource scarcity.
Purpose of the Study:
- To investigate how Pseudomonas putida adjusts its physiology under carbon (C), nitrogen (N), and phosphorus (P) stress at different growth rates.
- To elucidate the biochemical and elemental adjustments bacteria employ to sustain growth under suboptimal resource availability.
- To understand the manifestation of stoichiometric flexibility at the cellular level and its impact on ecosystem processes.
Main Methods:
- Utilized chemostats to impose varying dilution rates (approximating growth rates) and C:N:P ratios on Pseudomonas putida KT2440.
- Analyzed cellular elemental and biomolecular pools, oxygen consumption rates, and gene expression of terminal oxidases.
- Observed morphological changes, including aggregate and biofilm formation.
Main Results:
- Cellular composition varied with limiting resources at slow growth rates (0.12 h⁻¹), but showed convergence at faster rates (0.48 h⁻¹).
- Phosphorus and carbon limitation altered growth efficiency, impacting cellular C quotas and oxygen consumption.
- Differential gene expression of oxidases and aggregate/biofilm formation were observed as adaptive strategies.
Conclusions:
- Pseudomonas putida exhibits dynamic physiological adjustments to resource limitation, with distinct mechanisms at slow growth rates.
- At faster growth rates, bacteria converge towards an aggregative phenotype with similar elemental compositions.
- These adaptive strategies are crucial for microbial survival and influence elemental cycling in ecosystems.
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