Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 37: Active Matter (joint session BP/CPP/DY)

BP 37.8: Vortrag

Freitag, 16. März 2018, 11:15–11:30, H 1058

Harnessing emergence in bacterial populations: From biological mixing to active mechanics — •Anupam Sengupta — Institute for Environmental Engineering, ETH Zurich, Switzerland — Physics and Materials Science Research Unit, University of Luxembourg

At the scale of a single cell, interactions between a bacterium and its micro-environment represent a complex biophysical interface between phenotypic states (free-living planktonic or surface-attached sessile state) and external cues. In this talk I will discuss two recent works where we use experiments and modeling to elucidate how bacterial phenotype cross-talks with immediate micro-environment, and harnesses the emergent physics for biological functions. In the first case, we will see how Chromatium okenii, a 10 µm long purple sulphur bacterium, is capable of mixing over a meter thick layer of water in the Swiss Alpine lake, Lago di Cadagno. By changing the local fluid density, C. okenii is able to trigger convection rolls, creating a sustained well-mixed nutrient layer within an otherwise stratified lake. In the second instance, we will examine emergent geometrical and mechanical properties of a bacterial colony growing on a soft substrate. We show that such an expanding colony self-organizes into a “mosaic” of micro-domains consisting of highly aligned cells, before emerging into an active nematodynamic system. Interestingly, phenotypic traits - motility in the first and growth-induced stresses in the latter - couple with local hydrodynamics, to elicit important ecological functions at scales that can be orders of magnitude higher than single cells.