Article,
Responses of Escherichia coli bacteria to two opposing chemoattractant gradients depend on the chemoreceptor ratio
J Bacteriol, (January 2010)
DOI: 10.1128/JB.01507-09
Abstract
Escherichia coli chemotaxis has long served as a simple model of environmental signal processing, and bacterial responses to single chemical gradients are relatively well understood. Less is known about chemotactic behavior of E. coli in multiple chemical gradients. In their native environment, cells are often exposed to multiple chemical stimuli. Using a recently developed microfluidic chemotaxis device, we exposed E. coli cells to two opposing but equally potent gradients of major attractants, methyl-aspartate and serine. Responses of E. coli cells demonstrated that chemotactic decisions depended on the ratio of the respective receptor number, Tar/Tsr. In addition, the ratio of Tar to Tsr was found to vary with cells' growth conditions, whereby it depended on the culture density but not on growth duration. These results provide biological insights into the decision-making processes of chemotactic bacteria which are subjected to multiple chemical stimuli, and demonstrate the importance of the cellular microenvironment in determining phenotypic behavior.
