Weak synchronization and large-scale collective oscillation in dense bacterial suspensions.

Area of Science:

• Physics
• Biology
• Complex Systems

Background:

• Collective oscillatory behavior is common in nature, crucial for biological processes like embryogenesis and neural activity.
• Existing models often rely on long-range coupling via chemicals, electrical signals, or biomechanics for synchronization.
• Understanding synchronization mechanisms is key to comprehending biological self-organization.

Purpose of the Study:

• To discover a novel, weak synchronization mechanism in collective cell behavior.
• To investigate collective oscillations in dense bacterial suspensions.
• To elucidate the principles of self-organization in active matter systems.

Main Methods:

• Observation of collective oscillations in dense bacterial suspensions.
• Analysis of individual cell trajectories and averaged velocities.
• Development of a computational model of noisy self-propelled particles with local interactions.

Main Results:

• Identified collective oscillatory motion in millions of motile bacterial cells.
• Demonstrated that individual cells exhibit erratic movement, lacking inherent oscillation.
• Observed synchronized, in-phase oscillations on large scales, forming travelling waves.
• Validated findings with a model of local interactions, suggesting symmetry breaking as the driver.

Conclusions:

• A new, weak synchronization mechanism for collective oscillations has been discovered.
• This mechanism operates without long-range coupling or individual cell oscillations.
• Findings reveal a novel form of long-range order in active matter.
• The mechanism may inform strategies for controlling active matter and robotic swarms.