Streaming instability in growing cell populations.

Area of Science:

• Microbiology
• Biophysics
• Fluid Dynamics

Background:

• Cellular flows in confined environments can exhibit complex behaviors like streaming.
• Understanding these dynamics is crucial for fields ranging from industrial fermentation to biofilm formation.

Purpose of the Study:

• To investigate the phenomenon of cell streaming in bacterial populations.
• To elucidate the underlying mechanisms driving streaming instability in confined cellular flows.

Main Methods:

• Experimental observation of Escherichia coli (E. coli) proliferation in a microfluidic cell trap using time-lapse microscopy.
• Continuum modeling to simulate cellular behavior.
• Discrete-element simulations to analyze cell-cell and cell-substrate interactions.

Main Results:

• Observed distinct streaming patterns where fast-moving cell streams flowed around slower-moving cell clusters.
• Identified that cell adaptation to the microenvironment and changes in cell-substrate contact forces contribute to mobility.
• Demonstrated the interplay between these factors as the cause of streaming instability.

Conclusions:

• Cellular streaming in confined quasimonolayers is driven by a combination of slow environmental adaptation and dynamic cell-substrate interactions.
• This mechanism provides a fundamental explanation for observed streaming instabilities in bacterial populations.
• The findings offer insights into collective cell migration and pattern formation in biological systems.