Berlin 2012 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 9: Focus: Systems Biology of Bacteria (with jDPG)

BP 9.8: Vortrag

Dienstag, 27. März 2012, 12:15–12:30, E 020

Quorum sensing of motile bacteria in spatial confinement — •Jan Ribbe and Berenike Maier — Institut für theoretische Physik, Universität zu Köln, Köln, Germany

Microscopic structures influence the direction of swimming bacteria through hydrodynamic interaction. Thus we hypothesize that the concentration of bacteria in spatially structured environments is heterogeneous and can potentially lead to local accumulation of bacteria. Bacteria in groups often have different lifestyles than individuals. Controlled by quorum sensing and nutrient limitation, a well-defined fraction of cells differentiates into the competent state at high cell density.

Here, we intend to test the hypothesis whether the state of motility impacts on bacterial lifestyle. First we addressed the question whether competence and motility are mutually exclusive. We found that cells of Bacillus subtilis that have decided to become competent do not necessarily abolish motility. The rate of motility of competent cells decreases, but remains at 20±10 %. Next, we generated asymmetric microfluidic channels with volumes of 30 pl. We found that motile cells accumulate in the dead ends of the asymmetric channels and exhibit a pronounced concentration gradient. Active swimming promoted accumulation significantly. Using fluorescence reporters for the master regulator of competence, we found that the number of competent cells is strongly increased in dead ends where cell concentration is high. In future experiments we will characterize the spatio-temporal development of competence in microhabitats of different dimensions.