Swimming Motility Reduces Deposition to Silica Surfaces.

Area of Science:

• Environmental microbiology
• Biogeochemistry
• Fluid dynamics

Background:

• Bacterial transport and deposition in porous media are governed by complex physicochemical and biological factors.
• Understanding bacterial attachment is crucial for predicting microbial fate and transport in various environments.

Purpose of the Study:

• To investigate the impact of bacterial swimming motility on cell attachment to silica surfaces within model porous media.
• To quantify and compare the deposition rates of motile and non-motile bacterial strains under controlled hydrodynamic conditions.

Main Methods:

• Quantification of bacterial motility using microscopic image analysis and statistical methods.
• Analysis of bacterial cell deposition in radial stagnation point flow cells (RSPF) and 2D micromodels.
• Observation of cell approach and deposition dynamics near collector surfaces under defined flow conditions.

Main Results:

• Wild-type (DJ) bacteria exhibited active swimming (25.6 μm/s), impaired swimming (DJ77, 17.4 μm/s), and non-motile strains (JZ52, treated DJ).
• Motile bacteria (DJ) showed reduced surface attachment compared to non-motile or impaired-motility strains.
• Swimming motility limited cell contact with collector surfaces, particularly on upstream surfaces in micromodels.

Conclusions:

• Bacterial swimming motility is a key factor influencing deposition and transport in porous media.
• Active swimming reduces bacterial attachment, affecting their distribution and fate in environmental systems.
• Results highlight the ecological significance of motility in microbial transport processes.