title: A microfluidic device for quantifying bacterial chemotaxis in stable concentration gradients.
abstract: Chemotaxis allows bacteria to approach sources of attractant chemicals or to avoid sources of repellent chemicals. Bacteria constantly monitor the concentration of specific chemoeffectors by comparing the current concentration to the concentration detected a few seconds earlier. This comparison determines the net direction of movement. Although multiple, competing gradients often coexist in nature, conventional approaches for investigating bacterial chemotaxis are suboptimal for quantifying migration in response to concentration gradients of attractants and repellents. Here, we describe the development of a microfluidic chemotaxis model for presenting precise and stable concentration gradients of chemoeffectors to bacteria and quantitatively investigating their response to the applied gradient. The device is versatile in that concentration gradients of any desired absolute concentration and gradient strength can be easily generated by diffusive mixing. The device is demonstrated using the response of Escherichia coli RP437 to gradients of amino acids and nickel ions.
authors.affiliation: McFerrin Department of Chemical Engineering, Texas A&M University, TX, USA.
authors.forename: Derek L
authors.initials: DL
authors.lastname: Englert
authors.forename: Michael D
authors.initials: MD
authors.lastname: Manson
authors.forename: Arul
authors.initials: A
authors.lastname: Jayaraman
mesh_terms: D002630:Chemotactic Factors / Q000737:chemistry; D002633:Chemotaxis; D004926:Escherichia coli / Q000502:physiology*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods
chemical_list: D002630:Chemotactic Factors
references.citation: Proc Natl Acad Sci U S A. 2003 Apr 29;100(9):5449-54
references.pmid: 12704234
references.citation: Anal Chem. 2002 Apr 1;74(7):1537-45
references.pmid: 12033242
references.citation: Appl Environ Microbiol. 2009 Jul;75(13):4557-64
references.pmid: 19411425
references.citation: Methods Mol Biol. 2009;571:1-23
references.pmid: 19763956
references.citation: Microbiology (Reading). 2001 May;147(Pt 5):1383-1391
references.pmid: 11320140