Feeding flows of microorganisms attached to solid surfaces

Monday 04 Jan 21


Mads Boje Rode
PhD student
DTU Aqua


Thomas Kiørboe
DTU Aqua
+45 35 88 34 01


Anders Peter Andersen
Associate Professor
DTU Aqua
+45 35 88 34 11

Many aquatic microorganisms attach to solid surfaces while creating feeding flows that bring prey particles to them. A new paper in Physical Review Fluids explores how such feeding flows are affected by the proximity to the surface and the orientation of the flow-generating force.

To investigate the effects of surface proximity and force orientation, we use a simple low-Reynolds-number flow model. The presence of the surface reduces the clearance rate relative to the unbounded situation, and we show that the reduction is twice as large when the force is perpendicular to the surface as when it is parallel. When the force is perpendicular to the surface, the flow forms a toroidal eddy, and the resulting flow recirculation may lead to refiltration of water that has already been cleared for prey. We determine the recirculation times analytically, and we argue that recirculation is irrelevant for flagellates and ciliates since the recirculation time is long compared to the biologically relevant time scales. We conclude by discussing the advantages and disadvantages of perpendicular and parallel force orientation and the effects of prey diffusion and ambient flow.

Read the paper here: https://doi.org/10.1103/PhysRevFluids.5.123104

Rode M, Meucci G, Seegert K, Kiørboe T, Andersen A (2020) The effects of surface proximity and force orientation on the feeding flows of microorganisms on solid surfaces, Physical Review Fluids 5, 123104.

Header image: The ciliate Euplotes vannus observed while generating a feeding flow and sitting on a lump of organic material, and theoretical streamlines for perpendicular and parallel feeding flows, respectively.

24 JANUARY 2021