Quantitative analysis of single bacterial chemotaxis using a linear concentration gradient microchannel

• Published in: Biomedical microdevices Vol. 11; no. 5; pp. 1135 - 1143
• Main Authors: Jeon, Hojeong, Lee, Yongku, Jin, Songwan, Koo, Sangmo, Lee, Chang-Soo, Yoo, Jung Yul
• Format: Journal Article
• Language: English
• Published: Boston Boston : Springer US 01-10-2009; Springer US; Springer Nature B.V
• Subjects: Analytical chemistry; Bacteria; Biochemistry; Biological and Medical Physics; Biomedical Engineering and Bioengineering; Biophysics; Chemotaxis; Engineering; Engineering Fluid Dynamics; Escherichia coli; Escherichia coli - cytology; Hydrodynamics; Injections; Microbiology; Microfluidic Analytical Techniques - instrumentation; Nanotechnology; Velocity; Bacteria; Linear concentration gradient; Hydrodynamic focusing; Microchannel; Chemotaxis
• ISSN: 1387-2176; 1572-8781
• DOI: 10.1007/s10544-009-9330-8

A microfluidic device to quantify bacterial chemotaxis has been proposed, which generates a linear concentration gradient of chemoattractant in the main channel only by convective and molecular diffusion, and which enables the bacteria to enter the main channel in a single file by hydrodynamic focusing technique. The trajectory of each bacterium in response to the concentration gradient of chemoattractant is photographed by a CCD camera and its velocity is acquired by a simple PTV (Particle Tracking Velocimetry) algorithm. An advantage of this assay is to measure the velocity of a single bacterium and to quantify the degree of chemotaxis by analyzing the frequency of velocities concurrently. Thus, the parameter characterizing the motility of wild-type Escherichia coli strain RP437 in response to various concentration gradients of L-aspartate is obtained in such a manner that the degree of bacterial chemotaxis is quantified on the basis of a newly proposed Migration Index.