Paper Number
VP82 

Session
Pre-recorded Flash Presentations (virtual)

Title
Mechanical and structural analysis of channel networks in bacterial biofilms

Presentation Date and Time
All Week (Asynchronous) Any Time

Track / Room
Pre-recorded Presentation / Virtual

Authors (Click on name to view author profile)

  1. Geisel, Steffen (ETH Zurich, Laboratory of Soft Materials)
  2. Secchi, Eleonora (ETH Zurich, Biomatter Microfluidics Group)
  3. Vermant, Jan (ETH Zurich, Materials Departement)

Author and Affiliation Lines (in printed abstract book)
Steffen Geisel1, Eleonora Secchi2 and Jan Vermant1
1Laboratory of Soft Materials, ETH Zurich, Zurich 8093, Switzerland; 2Biomatter Microfluidics Group, ETH Zurich, Zurich 8093, Switzerland

Speaker / Presenter 
Geisel, Steffen

Keywords
experimental methods; computational methods; active materials; applied rheology; biological materials; colloids; interfacial rheology; microfluidics; rheology methods

Text of Abstract

Bacterial biofilms are formed by communities of microorganisms that are encased by a matrix consisting of self-produced, hydrated extracellular polymeric substances. Biofilm formation is observed in a large variety of microorganisms and provides a protected mode of growth. Recent advances show that biofilms are structurally complex, dynamic systems that exhibit different morphologies depending on the environmental conditions.[1] In certain growth conditions, large three-dimensional structures, which can be defined as channels, are found within biofilms. These channels show low resistance to liquid flow and therefore enable transport by advection.[2] Recent works identify the role of interfacial energy and mechanical instabilities as driving forces during biofilm morphogenesis[3], but the exact mechanism of channel formation is still unclear. Our work represents a step towards understanding the physical process of channel formation within a microbial biofilm.

We study how the adhesion of the biofilm to the substrate influences the formation of channels inside Pseudomonas aeruginosa biofilms grown under flow in microfluidic devices. We quantify the mechanical properties of the biofilm with active microrheological techniques. Our results show that biomass production, adhesion to the substrate and rheological properties control a mechanical buckling instability, which triggers the formation of folds and wrinkles. These three-dimensional structures can be identified as hollow channels in which bacterial movement is greatly facilitated and which rapidly increases the effective volume occupied by the biofilm. Combining methods and concepts from biology and material science sheds light on the physical process of channel formation inside bacterial biofilm grown in flow and enables us to predict and control the biofilm morphology.

[1] Flemming et al., The perfect slime. IWA Publishing, London, 2017
[2] Asally et al., PNAS, 109(46):18891–18896, 2012
[3] Yan et al., eLife 2019;8:e43920, 2019