Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 3: Bioimaging and biospectroscopy I

BP 3.1: Vortrag

Montag, 1. April 2019, 09:30–09:45, H11

Microviscosity of bacterial biofilm matrix characterized by quantitative fluorescence microscopy — •Valentin Dunsing, Tobias Irmscher, Stefanie Barbirz, and Salvatore Chiantia — Universität Potsdam, Institut für Biochemie u. Biologie, Potsdam, DE

Bacterial biofilms are surface-adherent communities of bacteria surrounded by an extracellular polymeric substance (EPS), which protects bacteria from antibiotics and pathogens. In this context, it remains unclear to which extent the EPS matrix imposes a physical barrier, e.g. to the transport of bacteriophages. To address this question, we have reconstituted the EPS of the bacterium Pantoea stewartii and investigated the diffusion properties of fluorescent particles using fluorescence correlation spectroscopy and single particle tracking. This approach allows to study the EPS spatial organization under various physico-chemical conditions. We show that small probes diffuse freely in the EPS with diffusion coefficients similar to those measured in water. In contrast, large probes are drastically slowed down, showing anomalous subdiffusion. The degree of confinement increases with EPS concentration. At physiological concentrations, beads of the size of bacteriophages are up to 100-fold slowed down compared to the dynamics in aqueous solution. To overcome this physical barrier, bacteriophages are equipped with EPS degrading enzymes. We show that upon EPS degradation, strongly confined diffusion rapidly turns to free diffusion. Thus, our approach allows the investigation of dynamic changes of the biofilm microviscosity and shows that the EPS imposes a probe-size dependent diffusion barrier under physiological conditions.