Mathematical Biology and Physiology Seminar (MaBPs)

This is a seminar to encourage mathematical research that helps us understand biology.

When: Spring Semester, 2014, Friday's, 12:00 - 13:00

Where: 114 McAllister Hall

Organizing Contact: Ying Yang

Participating Faculty: Andrew Belmonte, John Fricks, Chun Liu, Tim Reluga.

Mailing List: L-PSU-MABPS@lists.psu.edu (subscribe)

Next Talk

Date: April 25, 2014, 12:00 - 13:00

Speaker: Alexander Petroff, Rockefeller University

Title: Hydrodynamics and collective behavior of the tethered bacterium Thiovulum majus

Abstract: The ecology and dynamics of many microbial systems are shaped by how bacteria respond to evolving nutrient gradients and microenvironments. Here we show how the response of the sulfur-oxidizing bacterium Thiovulum majus to changing oxygen gradients cause cells to organize into large-scale fronts. We show that these dynamics occur in two steps. First, chemotactic cells moving up the oxygen gradient form a front that propagates with constant velocity. We then show, through observation and mathematical analysis, that this front becomes unstable to changes in cell density. Random perturbations in cell density create oxygen gradients, which lead to the formation of millimeter-scale fluid flows. We argue that this flow results from a nonlinear instability excited by stochastic fluctuations in the density of cells. These results provide a mathematically tractable example of how collective phenomena in ecological systems can arise from the individual response of cells to a shared resource.

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