February 25 , 2009
3 pm in Howey Physics Room N110

 

Harry L. Swinney
Center for Nonlinear Dynamics and Department of Physics
University of Texas at Austin

"Deadly competition between bacterial colonies"

 

We find that neighboring colonies of Paenibacillus dendritiformis bacteria growing on an agar gel mutually inhibit growth through secretions that become lethal if the level exceeds a well-defined threshold [1]. In contrast, within a single isolated colony, no growth inhibition is observed. However, growth inhibition and cell death are observed for a single colony if material extracted from the gel between two growing colonies is introduced outside the single colony. To interpret the observations we devised a simple mathematical model for the secretion of an antibacterial compound. Simulations of this model illustrate how secretions from neighboring colonies can be deadly while secretions from a single colony are not.

[1]  A. Be’er, H. P.  Zhang, E.–L. Florin, S. M. Payne, E. Ben-Jacob, and H. L. Swinney, Proc. Natl. Acad. Sci., to appear (2009).