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Specialized iNANO Lecture: Colloidal aspects of bacteria adhesion to solid and liquid interfaces

Professor Dr. Erik Reimhult, University of Natural Ressources and Life Sciences, Vienna

2019.11.18 | Trine Møller Hansen

Date Wed 20 Nov
Time 14:15 15:00
Location iNANO 1590-213, Gustav Wieds Vej 14, 8000 Aarhus C

Professor Dr. Erik Reimhult, Institute for Biologically inspired materials, University of Natural Ressources and Life Sciences, Vienna, Austria

 

Colloidal aspects of bacteria adhesion to solid and liquid interfaces

We present recent work on the adsorption of bacteria to solid and liquid interfaces, with emphasis on probing the role of pili on the attachment, motion, and biofilm growth of bacteria at nanopatterned solid surfaces.

Many bacteria interact with surfaces via long (µm) and thin (nm) tethers called fimbriae or pili. We investigated the role of fimbriae in the interaction of Escherichia coli (E. coli) under shear with surfaces displaying different densities of nanoscopic mannose or hydrophobic domains. We applied a newly developed extension of digital phase-contrast holographic microscopy and cytometry to map 3D trajectories of E. coli over these surfaces. This technique can be used to measure a position with ~50 nm precision at high time resolution, i.e., velocity, as well as size, orientation, and density. Flow shear forces acting on the bacteria were measured by resolving the laminar shear flow profile from the movement of free-flowing bacteria. This technique presents a new efficient tool to analyze bacteria interactions with surfaces quantitatively.

We show that fimbriated E. coli undergo a rolling motion on surfaces, irrespective of binding specificity, which is controlled by the fimbriae binding strength and the number of fimbriae forming bonds with the surface. The rolling motion slows down and eventually stops in response to increasing the flow rate. The loss of translational motion is caused by a shear force-induced push of the bacteria toward the interface. Pushing the bacteria closer to the surface increases the binding valency as shorter fimbriae now can bind to the surface. In contrast to other force-controlled binding mechanisms, e.g., catch-bonds, force modulation of the binding valency is generic.

Finally, we will discuss the meaning of “hydrophobicity” of bacteria in the context of their adsorption and the formation of biofilms at oil-water interfaces.

Host: Professor Duncan Sutherland, iNANO, AU

Specialized iNANO Lectures