Reducing phenotypic instabilities of a microbial population during continuous cultivation based on cell switching...

Area of Science:

• Microbiology
• Systems Biology
• Biotechnology

Background:

• Predicting microbial population dynamics and gene expression under dynamic conditions like continuous cultivation is difficult.
• Continuous cultivation can lead to genotypic and phenotypic heterogeneity within microbial populations.
• The arabinose operon in Escherichia coli serves as a model to study population diversification.

Purpose of the Study:

• To investigate microbial population diversification during continuous cultivation.
• To explore strategies for maintaining gene induction and controlling phenotypic heterogeneity.
• To model the arabinose operon induction in Escherichia coli under dynamic conditions.

Main Methods:

• Utilized flow cytometry to track green fluorescent protein (GFP) levels in Escherichia coli.
• Employed chemostat cultivation with glucose-arabinose co-feeding.
• Developed and used a segregat system for on-line monitoring and adaptive arabinose induction.

Main Results:

• Observed co-existing GFP-positive and GFP-negative subpopulations across various glucose-arabinose concentrations.
• Demonstrated that periodic arabinose induction in the segregat system maintained high induction levels for over 60 generations.
• Showed that this periodic strategy limited phenotypic diversity compared to continuous induction.

Conclusions:

• Steady forcing of cells into specific phenotypic states is less effective for population control than periodic induction.
• Allowing cells to periodically switch expression around a threshold offers a more robust strategy for stable population behavior.
• Adaptive, periodic control strategies can maintain desired gene expression while managing population heterogeneity.