Bioconvective pattern formation of Tetrahymena under altered gravity

Area of Science:

• Microbiology
• Biophysics
• Fluid Dynamics

Background:

• Bioconvection arises from microorganisms' negative gravitaxis, leading to density gradients and convective patterns.
• Gravity is a key factor, yet its role as an experimental variable in bioconvection is underexplored.
• Understanding hydrodynamic and biological dependencies on gravity is crucial for bioconvection research.

Purpose of the Study:

• To investigate how altered gravity affects bioconvective patterns in Tetrahymena.
• To analyze the hydrodynamic and biological factors influencing bioconvection under varying gravitational forces.
• To quantitatively assess changes in bioconvective patterns across different Tetrahymena strains.

Main Methods:

• Utilized a long-arm centrifuge to generate altered gravity conditions.
• Observed and recorded bioconvective patterns of Tetrahymena strains (T. pyriformis, T. thermophila, TNR).
• Analyzed patterns quantitatively using space-time plots and Fourier analysis.

Main Results:

• Bioconvective patterns formed above a critical acceleration (1.5 g) and were reversible.
• Pattern spacing decreased stepwise with increasing acceleration under supracritical conditions.
• The behavioral mutant TNR showed near-instantaneous changes in wave number with acceleration shifts, unlike wild-type strains.

Conclusions:

• Gravity significantly influences Tetrahymena bioconvection patterns.
• Cellular locomotor phenotypes, like avoiding response, play a critical role in bioconvective pattern formation.
• Findings provide insights into the interplay between gravity, cell behavior, and emergent patterns in microbial systems.