Wednesday, March 26, 2008, 2 PM
Thornton Hall D223

Results of a UVA-USGS Experiment Involving the Introduction of a Chemotactic, Engineered Pseudomonad into a Sandy, Solvent-Contaminated Aquifer

Ron Harvey, Ph.D.

Abstract

Because of our increasing dependence upon groundwater resources, there is an increasing need to remediate shallow contaminated aquifers. Xenobiotic contaminant that find their way into zones of low permeability can prove difficult to remove by traditional pump-and-treat technologies and degradation by native microbial communities can be slow and (or) result in buildup of toxic intermediates. Bioaugmentation involving addition to the aquifer of specialized bacterial consortia can facilitate more complete degradation and it is believed that chemotaxis, the ability of bacteria to swim towards higher concentrations of a chemical they perceive as beneficial to their survival, may expedite movement of introduced bacteria to where they are needed. However, there is no quantitative information about subsurface chemotaxis at the field scale and evidence has been largely anecdotal. This talk is about an injection-and-recovery study downgradient from the Massachusetts Military Reservation where a chemotactic, genetically engineered, solvent-degrading bacterium (Pseudomonas stutzeri) was introduced into a TCE-contaminated aquifer below constructed vertical gradients of acetate and nitrate. Its chemotactic migration in a direction perpendicular to groundwater flow was tracked and quantified. The field study demonstrated that chemotactic bacteria can move much faster in the aquifer than would be predicted from lab studies and that chemotaxis can be operative on a scale that would be useful in a stratified, contaminated aquifer.

Biography

Project Chief
Bacteria-Contaminant Interaction Project
USGS National Research Program (NRP)

The Civil Engineering seminar series is open to the University community.
Civil Engineering undergraduate students are especially invited to attend.