Long-range concentration gradients of multi-compounds for bacterial chemotaxis assay

Abstract

We present a diffusion-driven and long-range concentration gradient generator by using hydrogel as a porous membrane to prevent convection flows but allow the diffusion in a microfluidic device for the study of bacterial chemotaxis. Using the device, we characterize critical concentrations associated with chmotactic responses of cells that initially create a population band and then migrate in bands. In addition, we can find out the preferential chemotaxis of bacterial cells toward different carbon sources; glucose, galactose, mannose, over arabinose and xylose in this order, because the device can produce concentration gradients of multi-chemicals simultaneously as well.