title: Responses of Escherichia coli bacteria to two opposing chemoattractant gradients depend on the chemoreceptor ratio.
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 the 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. The responses of E. coli cells demonstrated that chemotactic decisions depended on the ratio of the respective receptor number of 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 the growth duration. These results provide biological insights into the decision-making processes of chemotactic bacteria that are subjected to multiple chemical stimuli and demonstrate the importance of the cellular microenvironment in determining phenotypic behavior.
authors.affiliation: School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Yevgeniy
authors.initials: Y
authors.lastname: Kalinin
authors.forename: Silke
authors.initials: S
authors.lastname: Neumann
authors.forename: Victor
authors.initials: V
authors.lastname: Sourjik
authors.forename: Mingming
authors.initials: M
authors.lastname: Wu
mesh_terms: D001224:Aspartic Acid / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism*; D002628:Chemoreceptor Cells / Q000378:metabolism*; D002630:Chemotactic Factors / Q000494:pharmacology*; D002633:Chemotaxis; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D011956:Receptors, Cell Surface; D012694:Serine / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D002630:Chemotactic Factors; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011956:Receptors, Cell Surface; C057331:Tar protein, E coli; C000607604:tsr protein, E coli; D001224:Aspartic Acid; D012694:Serine