(60e) Enhancing Bioremediation by Exploiting Bacterial Chemotaxis: 2-Dimensional Microcosm Studies

In-situ bioremediation is
limited by the inability to deliver the bacteria to the source of the chemical
contaminant which they will degrade.  Chemotaxis, the ability of some bacteria
to sense higher concentrations of chemical attractants and swim toward them,
can improve the effectiveness of bioremediation by directing bacteria toward contaminant
sources. In this study, a two-dimensional lab-scale model aquifer was used to
determine the effect of chemotaxis on the transport of bacteria exposed to a
chemoattractant concentration gradient in porous media.   The model
was packed with sand and an aqueous medium was pumped across horizontally,
simulating groundwater flow in a homogenous aquifer.  Sodium benzoate was
injected continuously to generate a steady concentration gradient transverse to
flow and chemotactic P.putida F1 or a non-chemotactic mutant of the same
species was injected below the attractant.  Samples were collected at the
end of the microcosm to provide vertical concentration profiles of the bacteria
and attractant.  The chemotactic bacteria center of mass was found to be an
average of 1.24 ± 0.86 cm closer to the attractant injection than the
non-chemotactic mutant. These results suggest that chemotaxis can improve the
transport of bacteria to contaminated zones, enhancing the effectiveness of in-situ
bioremediation.