Flow geometry effect on Pseudomonas fluorescens SBW25 biofilm structure

Area of Science:

• Microbiology
• Biomaterials Science
• Fluid Dynamics

Background:

• Biofilm formation is influenced by surface properties and fluid flow.
• Understanding these interactions is crucial for controlling microbial growth in various environments.
• Previous studies have explored surface material effects, but the combined impact of flow path geometry and material is less understood.

Purpose of the Study:

• To investigate how flow path geometry affects Pseudomonas fluorescens SBW25 biofilm structure.
• To compare biofilm formation on stainless steel electropolished (SSEP) and Teflon fluoroethylenepropylene (FEP) surfaces.
• To elucidate the combined effects of surface material and flow channel design on biofilm development.

Main Methods:

• Utilized a custom experimental setup with vertically oriented, millimeter-scale flow channels.
• Employed two channel types: straight and square-wave (zig-zag) flow paths.
• Quantified biofilm thickness and structure using Optical Coherence Tomography (OCT) and custom Matlab software analysis.

Main Results:

• Stainless steel electropolished (SSEP) surfaces consistently supported thicker, more uniform biofilms than Teflon fluoroethylenepropylene (FEP).
• Square-wave channels led to significantly thicker biofilms, particularly on SSEP, with enhanced accumulation along the downstream zig-zag path.
• FEP surfaces showed detachment in certain zig-zag sections, unlike the accumulation observed on SSEP.

Conclusions:

• Biofilm structure is critically dependent on the interplay between surface material properties and flow path geometry.
• SSEP surfaces are more conducive to robust biofilm accumulation, especially under complex flow conditions.
• Flow path design, particularly the introduction of geometric changes like zig-zags, can significantly enhance or disrupt biofilm formation depending on the surface material.