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DY: Fachverband Dynamik und Statistische Physik

DY 2: Active Matter I (joint session BP/CPP/DY)

DY 2.3: Vortrag

Montag, 16. März 2020, 10:15–10:30, HÜL 386

Motility induced transport in microbial environments — •Jayabrata Dhar, Arkajyoti Ghoshal, and Anupam Sengupta — Physics of Living Matter Group, Department of Physics and Materials Science, University of Luxembourg, 162 A, Avenue de la Faencerie, L-1511, Luxembourg City, Luxembourg

Despite their minuscule size, microbes mediate a range of processes in ecology, medicine and industry due to high local concentrations. Studies in aquatic ecosystems have demonstrated nutrient mixing via bioconvection by high concentrations of motile microbes [1] potentially impacts species distributions in natural settings. However, to date, we lack a systematic framework to capture the role of microbial traits (for instance, morphology or motility) on the onset and progression of bioconvection. Here, using different bloom-forming algal species as model organisms, we study how microbial traits underpin the onset of bioconvection and modulate mass transfer due to local density changes. Combining micro-PIV analysis of dispersed particles and auto-fluorescence imaging of algal cells, we quantify the emergent transport properties in real-time, revealing a plume-driven primary convective field. Interestingly, our results further capture relatively weak, secondary eddies that create local mixing patches with short lifetimes. Thus, bioconvection may alter the chemical environment of the microbes through distinct modes, impacting the distribution of nutrients, toxins or secondary metabolites, all of which could be vital for large-scale phenomena like harmful algal blooms.

[1] T. Sommer, et al., Geophysical Research Letters 44, 9424, 2017.