Fluid-driven Interfacial instabilities and turbulence in bacterial biofilms

5 years ago

Fluid-driven Interfacial instabilities and turbulence in bacterial biofilms

Amir Rmaile, Stefania Fabbri, Bart Gottenbos, Marilyn T. Ward, Nick G. Cogan, E. Michelle Starke, Marko De Jager, Paul Stoodley, Robert P. Howlin, Jian Li, Marcelo Aspiras

Biofilms are thin layers of bacteria embedded within a slime matrix that live on surfaces. They are ubiquitous in nature and responsible for many medical and dental infections, industrial fouling and are also evident in ancient fossils. A biofilm structure is shaped by growth, detachment and response to mechanical forces acting on them. The main contribution to biofilm versatility in response to physical forces is the matrix that provides a platform for the bacteria to grow. The interaction between biofilm structure and hydrodynamics remains a fundamental question concerning biofilm dynamics. Here we document the appearance of ripples and wrinkles in biofilms grown from three species of bacteria when subjected to rapid high-velocity fluid flows. Linear stability analysis demonstrated that the ripples were Kelvin-Helmholtz Instabilities. The analysis also predicted a strong dependence of the instability formation on biofilm viscosity explaining the different surface corrugations observed. Turbulence through Kelvin-Helmholtz instabilities occurring at the interface demonstrated that the biofilm flows like a viscous liquid under high flow velocities applied within milliseconds. Biofilm fluid-like behavior may have important implications for our understanding of how fluid flow influences biofilm biology since turbulence will likely disrupt metabolite and signal gradients as well as community stratification. This article is protected by copyright. All rights reserved.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1111/1462-2920.13883