Spatio-temporal patterns in growing bacterial suspensions.

Area of Science:

• Physics
• Biophysics
• Mathematical Biology

Background:

• Bacterial suspensions exhibit complex dynamics and phase transitions.
• Previous studies often focused on dense suspensions, neglecting the role of growth.
• Understanding emergent behavior in active matter requires models that incorporate growth dynamics.

Purpose of the Study:

• To develop a theoretical model for bacterial suspension dynamics and phase evolution during growth.
• To investigate the transitions between different phases (dilute, turbulent, heterogeneous) driven by bacterial proliferation.
• To elucidate the role of growth in self-organization and emergent patterns in active matter.

Main Methods:

• Hydrodynamic modeling of bacterial density, orientation, and fluid velocity.
• Incorporation of birth and death terms to simulate colony growth.
• Analysis of system transitions from low-density to high-density regimes.

Main Results:

• The model predicts sequential phase transitions: dilute, turbulent, and heterogeneous.
• Low-density regimes show local ordering, transitioning to clustering and turbulent phases with vortices.
• Increased density leads to inhomogeneous and random bacterial orientation, indicating heterogeneity.

Conclusions:

• Bacterial growth is critical for the emergence of distinct phases in suspensions.
• The model provides a comprehensive understanding of evolving patterns in growing bacterial colonies.
• This work bridges theory and experiment, offering insights into active matter systems driven by growth.