Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: Cell adhesion, mechanics and migration I (Joint session BP, CPP)
CPP 39.3: Vortrag
Mittwoch, 18. März 2015, 10:15–10:30, H 1058
Biogenic cracks in porous medium — •Arnaud Hemmerle1, Jörn Hartung1, Oskar Hallatschek1,2, Lucas Goehring1, and Stephan Herminghaus1 — 1Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany — 2Department of Physics, University of California, Berkeley, CA, USA
Microorganisms growing on and inside porous rock may fracture it by various processes. Most of the studies have been on the chemical aspects of biofouling and bioweathering, while mechanical contributions have been neglected. However, as witnessed by the perseverance of a seed germinating and cracking up a concrete block, the turgor pressure of living organisms can be very significant. It is the effects of such mechanical forces on the weathering of porous media that will concern us here. We designed a model porous medium made of glass beads held together by polydimethylsiloxane (PDMS) capillary bridges. The rheological properties of this material can be controlled by the curing conditions and the crosslinking of the PDMS. Glass and PDMS being inert to most chemicals, we are able to focus on the mechanical processes of biodeterioration, excluding any chemical weathering.
Inspired by recent measurements of the high pressure (≃0.5 Mpa) exerted by a growing population of yeast trapped in a microfluidic device, we show that yeast cells can be cultured homogeneously within porous medium and investigate then the effects of such an inner pressure on the mechanical properties of the sample. We observe crack propagation for a certain range of bead sizes and cohesiveness, showing a clear interaction between biotic and abiotic processes.