HR: 10:50h
AN: B31F-03    [PDF]
TI: Effect of Porous Media Particle Size on Bacterial Motility and Chemotaxis
AU: * Olson, M S
EM: mbstone@virginia.edu
AF: University of Virginia, Dept of Civil Engineering, P.O. Box 400742, Charlottesville, VA 22904-4742 United States
AU: Smith, J A
EM: jas9e@virginia.edu
AF: University of Virginia, Dept of Civil Engineering, P.O. Box 400742, Charlottesville, VA 22904-4742 United States
AU: Ford, R M
EM: rmf3f@virginia.edu
AF: University of Virginia, Dept of Chemical Engineering, P.O. Box 400741, Charlottesville, VA 22904-4741 United States
AU: Fernandez, E J
EM: erik@virginia.edu
AF: University of Virginia, Dept of Chemical Engineering, P.O. Box 400741, Charlottesville, VA 22904-4741 United States
AB: Many soil-inhabiting bacteria that degrade chemical contaminants are both motile and chemotactic. Chemotaxis refers to the ability of bacteria to sense pollutant concentration gradients in water and preferentially swim toward regions of high pollutant concentration, and is thought to be important in guiding subsurface microbial populations toward chemical contaminants. Bacterial motion consists of a series of smooth-swimming runs interrupted by changes in direction. In the presence of a chemical gradient, bacteria bias their frequency of changing direction and demonstrate longer run lengths in the direction of increasing attractant concentration. One concern when studying bacterial chemotaxis in porous media is that in small pores, the porous media may interrupt the extended run lengths of bacteria swimming in the direction of a positive chemical gradient. The purpose of this study is to examine how a decrease in particle size affects the motility and chemotactic response of bacteria traveling through porous media. We employ an innovative technique for noninvasive visualization of changes in bacterial density distributions in a packed column as a function of time. Paramagnetic magnetite particles are attached to the surface of {\it Pseudomonas putida} F1 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 300 $\mu$m. Experiments are conducted with both 250-300 $\mu$m beads and 90-150 $\mu$m beads. Bacteria labeled with magnetite are introduced into a specially designed chromatography column packed with glass-coated polystyrene beads. Bacterial migration is monitored over time using MRI, with and without the presence of a chemical gradient of trichloroethylene (TCE). Comparisons of the motility and chemotactic transport coefficients for {\it Pseudomonas putida} F1 cells traveling through different-sized samples of porous media in the presence of TCE will be presented and discussed. Results suggest a decrease in both motility and chemotaxis in the smaller-sized porous media.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Biogeosciences [B]
MN: 2003 Fall Meeting