Dresden 2026 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 11: Franco-German Session: Bacterial Biophysics I
BP 11.3: Vortrag
Dienstag, 10. März 2026, 10:00–10:15, BAR/0106
Nonlinear rheology of biofilm streamers: An eDNA-driven stress-hardening mechanism — Giovanni Savorana1, 2 and •Eleonora Secchi1 — 1ETH Zurich, Switzerland — 2Princeton University, US
Biofilms are aggregates of microorganisms embedded in a self-secreted polymeric matrix that protects the community from physicochemical insults, enhancing their resilience across environmental, industrial, and medical settings. Because most biofilms develop in moist, flowing environments, they are constantly exposed to hydrodynamic forces. Yet how biofilms withstand strong or fluctuating flow conditions remains poorly understood.
Our work investigates how biofilms assemble under flow and how their morphology and rheology adapt across different flow regimes. Using a microfluidic platform enabling reproducible formation and in situ rheological testing, we show that biofilm streamers-filamentous assemblies that develop within the bulk of the flow-display stress-hardening: under flow-induced axial stress, both the differential elastic modulus and the effective viscosity increase linearly. This non-linear rheological response is conserved across several bacterial species. We develop a physical model showing that extracellular DNA (eDNA) is the key component enabling this stress-hardening behavior, allowing streamers to withstand both rapid and sustained variations in hydrodynamic load. Our work advances the physical understanding of biofilm development, reveals the molecular drivers of their mechanical resilience, and informs strategies for preventing biofilm-induced clogging.
Keywords: Biofilm; Non-linear rheology; Extracellular DNA; Fluid dynamics; Microfluidics