Transport of Chemotactic Bacteria Through Porous Media in the Presence of a Chemical Concentration Gradient

EPA Grant Number: U916151
Title: Transport of Chemotactic Bacteria Through Porous Media in the Presence of a Chemical Concentration Gradient
Investigators: Olson, Mira S.
Institution: University of Virginia
EPA Project Officer: Lee, Sonja
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $87,231
RFA: STAR Graduate Fellowships (2003) Recipients Lists
Research Category: Fellowship - Environmental Engineering , Academic Fellowships , Engineering and Environmental Chemistry


The objective of this research project is to quantify the effect of chemotaxis on bacterial migration through a packed column. Chemotaxis refers to the ability of bacteria to sense pollutant concentration gradients in water and preferentially swim toward regions of high pollutant concentration.


I employ an innovative technique to quantify the chemotactic response of bacteria to pollutant concentration gradients in porous media. Paramagnetic magnetite particles are attached to the surface of Pseudomonas putida cells using an antibody. Bacterial distributions within a column of glass-coated polystyrene beads are imaged using magnetic resonance imaging (MRI), with a spatial resolution of 330 mm, providing information that was previously unattainable. This improved resolution is essential as it is believed that chemotaxis occurs in the presence of very localized microscopic gradients. Bacterial distributions are compared for columns with and without the presence of a chemical gradient, and the results are used to determine the effect of chemotaxis. This new technology enables us to view changing bacterial concentrations at a very small scale, and it will help us to better understand the process of chemotaxis. I hypothesize that the chemotactic response of bacteria will be important in regions with a defined attractant gradient and that our measurement and analysis will verify that this process occurs in porous media. Many of the soil-inhabiting bacterial species capable of transforming pollutants into nontoxic products also exhibit chemotaxis toward the pollutant chemicals. If chemotaxis proves to be a significant transport mechanism for bacteria, then remediation strategies should consider not only the degradative abilities of bacteria, but also the chemotactic abilities. Therefore, chemotaxis may play a significant role in natural, as well as engineered subsurface remediation.

Supplemental Keywords:

fellowship, chemotaxis, bacterial migration, Pseudomonas putida, chemotactic bacteria, chemical concentration gradient, subsurface remediation.

Progress and Final Reports:

  • 2003
  • 2004
  • Final