Thursday, October 23, 2008, Condensed Matter Biological Physics Seminar, Prof. Hanna Salman, Univ. Pittsburgh, "Population Effects on Bacterial Thermotaxis", 4:30 PM, Doherty Hall A310, CMU

Abstract

We have developed new methods to explore the response of E. coli to temperature changes. A strong correlation between the population density and the response to a temperature gradient is observed. Bacteria that are grown below a critical concentration, in batch-mode cultures, swim towards warm regions when subjected to a temperature gradient. Above that concentration, they swim towards colder regions. Our findings indicate that a secreted intercellular signal, glycine, mediates this switch through methylation of Tsr receptors. At high bacterial concentration, the switch is reinforced by an inversion of the Tar/Tsr expression ratio.